i've ran a couple of 20th anniversaries. One had almost every kind of bolt on possible, except a fmic. We ran from a roll, and he would pull about a car (those turbos spool up fast down low) but i would easily be a car ahead of him by 80mph and pulling on him. This was when i was stock.
I also ran a 20th anniversary with chip, intake, turbo back, bov and we did it from a 5mph roll, and he got about 1 car length on me and at about 70 i was a car, 90 about two cars and pulling pretty hard. We slowed down, he told me his mods and i told him how i was stock and he commented how my car is a beast.
I also ran a 20th anniversary with Giac X+, intake, and catback (dont know what else), but we did it from a roll, 40 mph and we would be even for a second and i would start walking him pretty easily. This was the only race that i actually got to race from a stop, and i got a pretty weak launch (with a bog) but even with my bad launch, and his FWD traction problem, by 70-80 mph i was a good 5-6 cars in front of him. I had my chip intake at the time. Now i also have lighter rims (-35 to 40 pounds total from stock). I will find the link to this race because i got it on video so that you guys can see it. Hopefully i can find the race.
VIDEO ---> http://www.hsaloyola.com/r32/r32gti.mov
20th ANNIVERSARY vs. Me (R32)
I should technically run a low/mid 13 @ 101-103 mph with my mods. I am right in par with a stage 2-2.5 WRX (i would like to see how id do against one after 100mph). This is the reason why i find it hard that a GLI (which is a bit heavier than the 20th GTI but has the same engine) will be able to beat a stage 2 wrx with just basic bolt ons (chip, intake, exhaust, turboback(downpipe+catback), diverter valve, etc.
No offense, i love the GLI, i own an R32... but a GLI with those mods will easily take out a stock wrx or anything lower than a stage 2 from a roll, but probably have a hard time from a stop.