I can run 1.33s pretty consistently with my own setup. I did a 1.32.88 once, but never seen another 1.32 since. I've seen replays of 1.31 laps, and they just hold a few more mph through some of the turns. I can take every turn just as fast as them, just not all on the same lap

The stock setup is pretty decent actually, and not far off what my custom setup. The biggest difference I notice was reducing caster down to about 2 degrees or so. Doesnt make much sense, but the front seemed to stick much better after that.
It takes a while to get used to it, but I like the turbo much better. In my experience, GTi races are usually decided on the 1st lap, after that I wach the guy ahead of me slowly run away because he can run a quarter sec faster than me, and I do the same to the guy behind me. With decent drivers in turbos, you have guys making more little mistakes, getting a bit sideways here and there, that you can pounce on.
Going back to the GTi you realize just how painfully slow it is. I start falling asleep on the back straight.
Modding is pretty fun too. I've got a 832lb, 40000hp GTi that will run a 33 second lap

. I also tried to make a Viper. Took the turbo and made it 3600lb with a 420hp 8.0L naturally aspirated V4. Since theres no way to make the tires wider, it prolly came out closer to a 60s vette. It's never fully under control except for a few seconds on the back straight.