One has to wonder what the internal quality of the dampers is at that price, $950 with camber plates? Have you guys run these on a shock dyno? My GC/Koni setup on my M3 is getting a little tired feeling...
I think the RSS kit should work well on an otherwise stock GTI for DE days. If it's going to be turned into a real race car though I wouldn't presume to say what will or won't work, but instead ask someone who really races these cars what a good starting point is and gain more insight through testing. I would suggest much higher spring rates than my article for a dedicated track car. My GTI was doing dual duty. My M3 runs 650/600 springs, but will mostly see the track. That being said, I got great results in the GTI with softer springs and improved roll center through aftermarket spindles that lowered the ball joint attachment points - sport spindles. Totally illegal in probably any class you'd enter the car in, but lots of fun at DE's!
If the goal is club racing I'd start with what the OP has, a 944, or a BMW as there's a lot more support, knowledge and proven race parts out there on those cars, not to mention way more organizations that race those cars.
No need... ISC use to have dyno charts on their site. They work and the quality speaks for themselves based on selling them for two years with ZERO damper failure from build quality... The only failure we have seen is ONE from the rear damper not being set right and the shock continually bottoming out until it literally blew the seals.. And ISC warrantied it.... I am probably putting them on my E46 Touring since my Koni's are DOA in back and the ISC's actually feel better on track than any Koni set up I have been on. Feel wise they remind me of a JRZ... And I am somewhat of a snob with suspension bits...
The reason your Koni/GC set up is feeling tired is you are running spring rates that are about the limit of the Koni Damper, which kills the damper in short order from overworking it.. Not to mention the rates you are running are not correct, front to rear, either for a E36 track car, more suited for autocross. For track use with a Koni set up we recommend, front 450, rear 550 or 600, MAX rates you can run safely for track 550 front and 650-700 rear with all dampers set at max hard in back with the 700 pound springs and 3/4 with the 650 rate.
RSS vs ISC the ISC is a better damper... H&R tends to not use great dampers unless you get one of the really expensive units... Not to mention the ISC is compression and rebound adjustable via one knob.. Koni is just rebound only. You can adjust the ISC dampers and actually change the car's handling which you cannot do with a Koni or many other budget coil over kits like H&R, ST, KW, Koni basic kits etc..
Typically you have to be careful how much rate you run on any damper they are only engineered to run X rates and anything higher will wear the internals out fairly fast if you over spring them. As in 1-2 years of track use then they need replacing or a rebuild...
The OP already tracks his 944 he is asking about his CUSTOMERS GTI not his car. A 944 is not a cheap car to track they are more maintainace intensive than an E36 of any model. I worked in a Porsche shop years ago and an older 911 cost less to maintain than a 944. A clutch job on ANY 944 model is a labor nightmare...And a well set up E36 325is is far faster than a 944...
If you would like a ride in a car with ISC's set up properly I will be at Road Atlanta, and VIR a fair amount this year, probably with the E36M3 of my buddies with the ISC set up or my Wagonator. One ride is normally all it takes.. I have taken a few people out and they have all been impressed with the car....these are guys with track cars and instructors...
And maybe a Mk V with them...
