Opinion Needed

[WillyDaP]

Sam,
You might look into the CMS roll bar as they also can provide panels that substitute for the factory ones ( saving those if the rollbar is later removed ) . I have a couple of friends who have done those and they also can match many Porsche colors. Just another possible option for you, but both of my buddies had the bar professionally installed.

[J-Dub]

Great conversation already going on here so I will try to add in the details that I have experience with as well as point out some differences between the GTS 4.0 and GT4.

General relationship to keep in mind:
As you add spacer shims to the lower control arms to gain Camber you also gain caster as the wheels move forward in the wheel well. This is why the bushing where the tension arm connects sometimes has an alternate hole or maybe even a full eccentric. If you add a bunch of shim you need to use the alternate hole to move the front wheel backwards.
Also if you do all of your camber gain from shims only, no camber plates, you will significantly widen your track and potentially run out of threads on your tie rod ends. This may limit your tire size.

As you lower the car you gain camber.

Front suspension:
The first logical step for track alignment is to add Camber plates to the front of a GTS. The will give you up to ~2.5/2.6 degrees camber but narrow your front track. To compensate for the narrowed track I have installed 10mm wheel spacers. Wheel spaces add scrub radius to the front end and though it is okay, it is not desirable.

The GTS has fixed length control arms while the GT4 has adjustable length control arms. The long term solution for the GTS track rat is to do both camber plates and adjustable lower control arms. I am using Tarett camber plates and have just purchased Tarett GT3 cup series, rubber bushings, lower control arms. I will install the LCAs this week end and attempt to adjust a nice balance of caster/camber/track with. There are other lower cost LCA solutions out there but these are what I chose.

Rear suspension:
The rear knuckle is different between a GT4 and GTS, the GTS typically does not "need" aftermarket rear toe links to get to 2.5 deg camber with appropriate toe in. There are some advantages though including bushings with less deflection and spacers that move the inside heim joint forward instead of keeping them centered. This is what TPC does and Tarett has this solution in the works. Aftermarket rear toe links also have the advantage of putting the inside eccentric all the way in so you are lengthening the toe link for less bump steer allowing you to run less rear toe in.

Shocks/dampers/springs:
The GT4 has threaded body coilover type strut bodies making ride height and spring changes easy. The GTS does not have this, they have a more traditional strut body that is non adjustable. KW and H&R make lowering spring kits where the front struts get sleeved with a threaded body so the ride height becomes adjustable. I have the H&R VTF kit and the rear is too low for my preference. My car came with a two finder gap between the tire and fender, I prefer 1 finger. The H&R rear spring has a zero finger gap between the rear tire to fender. There are solutions here including adding a spacer under the spring but for me this is a work in progress. Currently I have a rubber packer in the top coil spring in the rear. This did two things, raise the rear a bit giving the car some rake and slightly increase the rear spring rate in a progressive way. My last track day, last Saturday, the car turned in better than ever. I might be on to something here.

One option we have for the GTS cars is the Bilstein B16 kit, it is a complete kit that is PASM, threaded bodies with linear springs. This kit also gives the option to change springs to any rate we would desire. The possible downside to this kit Vs say the Tractive is the damper is essentially the same thing as what comes stock, it is not an upgrade like the Tractive system is. Then again the Tractive system is really nice but is adult money so there is that.

Brakes:
I would add track pads on your stock rotors and wear them out first. The stock rotors with the holes develop cracks and do seem to wear down quickly. Aftermarket two piece rotors are available from AP, Giro and Paragon among others. I went with Giro because for the GTS 350/330mm brakes they make a kit to go to 350/350mm. GT4s come with 380/380mm for reference.
Brake pad selection is great on this platform but myself and others here have had great success with Ferodo 3.12 pads, I have heard great reviews from Pagid and Endless pads as well. The 3.12s have great power and modulation when cold or hot, they don't fade on track and they are pretty quiet and the dust is really not bad. On other platforms I have tried pads from Porterfield, Glock and Carbotech and never found such a great mix.

I have not yet tried any SS brake lines so have not comment there. On my GTS I have removed the dust shields from behind the rotors as little pebbles kept getting between them and the rotors and made terrible noises. The GT4 has much smaller dust shields for what it is worth. Initially I considered trying to use the GT4 dust shields but the knuckle is different enough that this would not work. The brake cooling ducting also blows directly at the dust shields so this might help cool the rotors. To compensate for not dust/heat shield I added little pieces of heat insulation to the balljoint boots.

Alignment:
I am currently on a 2.5/2.0 camber alignment, previously was at 2.6/2.4. I had the dealer replace my windshield and they "had" to do a wheel alignment and brought the rear back to Porsche specs. People talk about 3.0/2.5 to be a good starting place then adjust for your particular track, car, tires, driving style etc. I am personally thinking Tim has it right and square or closer to square is the sweet spot. This is a work in progress but my last set of tires I completed had even wear up front and the rear were more worn on the outside shoulder. For sure a little toe out up front and toe in at the rear. Reference the TPC website for their recommendations as well.

Over axle pipes:
No question here get heat insulated pipes for a car that sees track duty, jet hot coating is not sufficient. I chose the resonated pipes for a more mellow tone.

Engine flash:
There is a lot to gain on the GTS as there is a closing of the throttle body at high RPM to make sure it has less power than the GT4. Some are not comfortable with changing the engine calibration however those are more often collectors and speculators but track people typically want all the power. I went with Softronics and am very happy with it. Scott has options for how the exhaust flap works, removal of auto stop/start, cylinder deactivation, lighter cold start etc. and I can flash back and fourth as often as I like myself.

Wheel size:
Yes 18" will work for a GTS however they won't work with your GT4 friends and I wanted to ability to trade wheels around so I went with 19". These cars have a good TPMS system and I do monitor them on the track. When switching wheels you must go into the TPMS system on the dash and choose a different wheel so the system with initiate the re-learn. The system needs to identify different wheel speeds to sync so make sure you take turns after you swap wheels, weather that means a big parking lot and do circles or drive through neighborhood roads where you can do several rights and lefts.

The TPMS light will be on at 24 psi(1.7 bar) no matter what you set for your target pressure in your TPMS configuration. I have not yet found a solution for this. If my target hot temps on 200 TW tires is 28-30 I will often start at 23-24 before my session.

My street tires are 245/295 on my stock 20" wheels, my track tires are 255/285. Apex has suggestions as well as many others on these discussion boards. I want to say more tire is better but then more aero is better and I have a no wing car so I am not sure what tires size is best for your situation.

DSC controller:
This is great, I have done A B testing several times and like the DSC much better than the stock controller. Consider the stock controller to keep the damper at a fixed value depending on the mode you are in VS the DSC that is dynamically changing the damper for all conditions. What I said about the stock controller is not technically correct but use that as an analogy.

Front strut tower:
My understanding is the 718 is much more beefed up here compared to the 991/981 generation. Not saying the strengthening plates are not a good idea or that failures don't happen. Just know they are not glass like and the average person will not experience a failure.

I am sure there is more to add but feel free to ask additional questions or provide alternate opinions to and thing I have stated above.

Thanks,
Jeremy

[blueline]

That's an excellent assessment Jeremy! Wow! Too bad I'm not in Phoenix so that I could soak up some of your knowledge first hand. Of course, that would assume that my brain was capable of such a feat...

Much thanks!

[J-Dub]

We may not live in the same city but we can share knowledge and experiences here and I am very fortunate for that!

[WillyDaP]

Great info , but the one item I would ask is if you want your car to stay under warranty, as most Dealers will let you do minor items like pads , camber plates , etc., but once you flash the engine some will void said. Just a word of caution since your GTS is a brand new 2025.

[Sam_Flat6]

Sam,
You might look into the CMS roll bar as they also can provide panels that substitute for the factory ones ( saving those if the rollbar is later removed ) . I have a couple of friends who have done those and they also can match many Porsche colors. Just another possible option for you, but both of my buddies had the bar professionally installed.

Yes. The ones I’m considering are CMS, Cantrell, and BBI.

[Sam_Flat6]

Great conversation already going on here so I will try to add in the details that I have experience with as well as point out some differences between the GTS 4.0 and GT4.

General relationship to keep in mind:
As you add spacer shims to the lower control arms to gain Camber you also gain caster as the wheels move forward in the wheel well. This is why the bushing where the tension arm connects sometimes has an alternate hole or maybe even a full eccentric. If you add a bunch of shim you need to use the alternate hole to move the front wheel backwards.
Also if you do all of your camber gain from shims only, no camber plates, you will significantly widen your track and potentially run out of threads on your tie rod ends. This may limit your tire size.

As you lower the car you gain camber.

Front suspension:
The first logical step for track alignment is to add Camber plates to the front of a GTS. The will give you up to ~2.5/2.6 degrees camber but narrow your front track. To compensate for the narrowed track I have installed 10mm wheel spacers. Wheel spaces add scrub radius to the front end and though it is okay, it is not desirable.

The GTS has fixed length control arms while the GT4 has adjustable length control arms. The long term solution for the GTS track rat is to do both camber plates and adjustable lower control arms. I am using Tarett camber plates and have just purchased Tarett GT3 cup series, rubber bushings, lower control arms. I will install the LCAs this week end and attempt to adjust a nice balance of caster/camber/track with. There are other lower cost LCA solutions out there but these are what I chose.

Rear suspension:
The rear knuckle is different between a GT4 and GTS, the GTS typically does not "need" aftermarket rear toe links to get to 2.5 deg camber with appropriate toe in. There are some advantages though including bushings with less deflection and spacers that move the inside heim joint forward instead of keeping them centered. This is what TPC does and Tarett has this solution in the works. Aftermarket rear toe links also have the advantage of putting the inside eccentric all the way in so you are lengthening the toe link for less bump steer allowing you to run less rear toe in.

Shocks/dampers/springs:
The GT4 has threaded body coilover type strut bodies making ride height and spring changes easy. The GTS does not have this, they have a more traditional strut body that is non adjustable. KW and H&R make lowering spring kits where the front struts get sleeved with a threaded body so the ride height becomes adjustable. I have the H&R VTF kit and the rear is too low for my preference. My car came with a two finder gap between the tire and fender, I prefer 1 finger. The H&R rear spring has a zero finger gap between the rear tire to fender. There are solutions here including adding a spacer under the spring but for me this is a work in progress. Currently I have a rubber packer in the top coil spring in the rear. This did two things, raise the rear a bit giving the car some rake and slightly increase the rear spring rate in a progressive way. My last track day, last Saturday, the car turned in better than ever. I might be on to something here.

One option we have for the GTS cars is the Bilstein B16 kit, it is a complete kit that is PASM, threaded bodies with linear springs. This kit also gives the option to change springs to any rate we would desire. The possible downside to this kit Vs say the Tractive is the damper is essentially the same thing as what comes stock, it is not an upgrade like the Tractive system is. Then again the Tractive system is really nice but is adult money so there is that.

Brakes:
I would add track pads on your stock rotors and wear them out first. The stock rotors with the holes develop cracks and do seem to wear down quickly. Aftermarket two piece rotors are available from AP, Giro and Paragon among others. I went with Giro because for the GTS 350/330mm brakes they make a kit to go to 350/350mm. GT4s come with 380/380mm for reference.
Brake pad selection is great on this platform but myself and others here have had great success with Ferodo 3.12 pads, I have heard great reviews from Pagid and Endless pads as well. The 3.12s have great power and modulation when cold or hot, they don't fade on track and they are pretty quiet and the dust is really not bad. On other platforms I have tried pads from Porterfield, Glock and Carbotech and never found such a great mix.

I have not yet tried any SS brake lines so have not comment there. On my GTS I have removed the dust shields from behind the rotors as little pebbles kept getting between them and the rotors and made terrible noises. The GT4 has much smaller dust shields for what it is worth. Initially I considered trying to use the GT4 dust shields but the knuckle is different enough that this would not work. The brake cooling ducting also blows directly at the dust shields so this might help cool the rotors. To compensate for not dust/heat shield I added little pieces of heat insulation to the balljoint boots.

Alignment:
I am currently on a 2.5/2.0 camber alignment, previously was at 2.6/2.4. I had the dealer replace my windshield and they "had" to do a wheel alignment and brought the rear back to Porsche specs. People talk about 3.0/2.5 to be a good starting place then adjust for your particular track, car, tires, driving style etc. I am personally thinking Tim has it right and square or closer to square is the sweet spot. This is a work in progress but my last set of tires I completed had even wear up front and the rear were more worn on the outside shoulder. For sure a little toe out up front and toe in at the rear. Reference the TPC website for their recommendations as well.

Over axle pipes:
No question here get heat insulated pipes for a car that sees track duty, jet hot coating is not sufficient. I chose the resonated pipes for a more mellow tone.

Engine flash:
There is a lot to gain on the GTS as there is a closing of the throttle body at high RPM to make sure it has less power than the GT4. Some are not comfortable with changing the engine calibration however those are more often collectors and speculators but track people typically want all the power. I went with Softronics and am very happy with it. Scott has options for how the exhaust flap works, removal of auto stop/start, cylinder deactivation, lighter cold start etc. and I can flash back and fourth as often as I like myself.

Wheel size:
Yes 18" will work for a GTS however they won't work with your GT4 friends and I wanted to ability to trade wheels around so I went with 19". These cars have a good TPMS system and I do monitor them on the track. When switching wheels you must go into the TPMS system on the dash and choose a different wheel so the system with initiate the re-learn. The system needs to identify different wheel speeds to sync so make sure you take turns after you swap wheels, weather that means a big parking lot and do circles or drive through neighborhood roads where you can do several rights and lefts.

The TPMS light will be on at 24 psi(1.7 bar) no matter what you set for your target pressure in your TPMS configuration. I have not yet found a solution for this. If my target hot temps on 200 TW tires is 28-30 I will often start at 23-24 before my session.

My street tires are 245/295 on my stock 20" wheels, my track tires are 255/285. Apex has suggestions as well as many others on these discussion boards. I want to say more tire is better but then more aero is better and I have a no wing car so I am not sure what tires size is best for your situation.

DSC controller:
This is great, I have done A B testing several times and like the DSC much better than the stock controller. Consider the stock controller to keep the damper at a fixed value depending on the mode you are in VS the DSC that is dynamically changing the damper for all conditions. What I said about the stock controller is not technically correct but use that as an analogy.

Front strut tower:
My understanding is the 718 is much more beefed up here compared to the 991/981 generation. Not saying the strengthening plates are not a good idea or that failures don't happen. Just know they are not glass like and the average person will not experience a failure.

I am sure there is more to add but feel free to ask additional questions or provide alternate opinions to and thing I have stated above.

Thanks,
Jeremy

So appreciate the detailed write up. A lot of what you mentioned is very helpful to a new owner like me so I can avoid mistakes and learn how to properly dial it in. I need to digest all of this information and what others have shared so I can build out my GTS in a thoughtful way and not throw parts at it. At the moment I will continue reading and listening. As I get past break-in mileage, I will re-engage as I get on it. I’m in Phoenix to track on private track days given I relocated to Reno. PM and I will reach out to you and maybe we can meet up if you’re open to it.

Sandeep ‘aka Sam’

Ps. Already ordered some interior stuff to protect seats, etc. Ha.

[J-Dub]

Regarding the front control arms and the bushing that the tension arms connects to, I wanted to add a picture for reference to better clarify what I was trying to explain. In this image this is the front right control arm and the direction of travel is to the right of the picture. This is my stock GTS arm vs the aftermarket arm, the aftermarket has two holes to give the user options. The center hole is correct if the user is going after low camber, more of a stock camber setting. The alternative hole is correct for a track alignment, more aggressive camber.

Edit: wanted to add that when you are installing the arms with your estimated number of shims, which holes to use might be somewhat obvious. In my case I tried 12mm of shim and when I was offering up the tension arm it the hole lined up perfectly with the alternate hole in the LCA. Currently I am at 10mm of shim as I started to be concerned with the tie rod thread engagement. Once I get the alignment close I will count the threads to be sure.

IMG_5765.jpeg (5.83 MiB) Viewed 3661 times

[Sam_Flat6]

Regarding the front control arms and the bushing that the tension arms connects to, I wanted to add a picture for reference to better clarify what I was trying to explain. In this image this is the front right control arm and the direction of travel is to the right of the picture. This is my stock GTS arm vs the aftermarket arm, the aftermarket has two holes to give the user options. The center hole is correct if the user is going after low camber, more of a stock camber setting. The alternative hole is correct for a track alignment, more aggressive camber.

IMG_5765.jpeg

Thanks for the pic. That’s what I’ve read and understand as well. I will be bringing the car to Phoenix soon. My big garage and tools are still there. Hope to catch up with you if you’re open to it.

[J-Dub]

Looking forward to it!

Hope to catch up with you if you’re open to it.