darnit. I had a whole thing typed, then hit ctrl-R instead of ctrl-t and wiped it all out.
so now the quick summarization without humorous quips:
starting with stock engine and brakes, with 195/60-14 Azenis and Hawk HP-Plus, I could push the car to about 9 tenths at BHF (Blackhawk Farms Raceway) and still stick without any problems. I was nearing 10/10ths, when the previous owner's use of RTV on the headgasket caused the engine to not send anymore oil to the head, and things just turned sour. I'd also run some autoXes on the same tires, and everything was pretty good.
So, I rebuilt an engine, (108whp on a dynojet), and got a kaaz lsd (with WPE 4:778:1 R&P), and carbotech xp10/xp8 front/rear brakes. Turned the 195/60-14's into beautiful smoke-makers. really had to feather the throttle, and could not give 10-tenths without breaking loose.
got some 14x7 -9 rewinds, and some 225/50-14 hoosiers. (on sale cheap, because the R6/A6 had just come out, and they were clearancing their old stock.) I had NRCA's and AGX's on the front, the car was lowered, so i did have to roll the front fenders a bit, and even use 5mm spacers on the front to not rub. But the car stuck. I could actually get 10-tenths out of this car at BHF, took FTD at a couple autoXes, usually first in class, and once even ftd on pax AND raw. Took it to BIR (Brainerd Int'l Raceway in MN) but on some Hankook R-comp slicks of the same size, and was able to get 11-tenths out of it, but the brakes were in need of more.
So, I consult with Bob at Drift Office, and then apply his recommendation: TODA cams (264/256), FPR, and a header. this tuned to 133.0whp on a (Dyno Dynamics eddy-current dyno). I added brake ducts and upgraded from the Carbotechs to some Raybestos ST43 front, and 41 or 42 in the rear (sorry, I can't remember). World of difference in the brakes, and I was starting to find the edge of traction on the 225/50-14's. Around this time, I also got some 255/40-13s on some panasport knockoffs (can't remember if they're rota RB's or older-style rewinds).
I found a few things when running the 225's, and even the 255's, that caused a bit of consternation/frustration at times. Tthe car gassed up with me in it weighed 2495lbs. In short, very tight autoXes, I used the 255s because they were short and helped gearing, and heated up quickly. when the course was wider open and faster, I'd use the 225's, and do alright as well. my biggest problem was that with that much rubber on the ground, it wouldn't heat up in time to make itself super sticky, and an S2K CR would start beating my times.
Granted, he had brand new R6's and I had not bought new rubber in some time. that's my excuse and I'm sticking to it. Then, a bolt holding an NRCA snapped when going through a roundabout, and my car endured structural damage so I haven't raced it since (project is now underway, but that's a different story).
I'm not sure what power and torque you're putting to the ground, but If it's anything like mine (and I think it is, maybe even better) think the HUGE availability of 205/50-15 tires in different compounds and tread patterns might be worth looking into. If you can fit a 225 in there without going crazy with a hammer , I think it's worth it for HPDE/TimeAttack stuff. However, the 225's can get to be pretty heavy tires, and in an autoX might end up slowing your acceleration more than the grip they provide is worth..
but that's the fun of the sport, the whole balancing act...