Hi everybody:
My English is not good, but I will try, with the help of a translator, make me understand.
I too am owner of a Cosworth Stage 2, without the stage 1. In other words, take the oem exhaust line. I'm wearing for 1 month. Day 14 is trackday at Montmelo and try there. We'll see. But I still take 215 tires.
http://fa20ownersclub.foros.bz/t129-cosworth-install
Cheers