gsr trannies suck for boost period. you will end up trapping in fifth gear at like 116mph. For boost, from MY experience, the LS transmission is best. nice long gears. As far as engine/turbo setup... I had fully built gsr with a full-race pro am kit. The engine was re-sleeved, stock bore, 9:1 cp, built head with stock port and itr cams. on 22psi and c12 race gas i made 551whp, 383wtq. Now on the street, it sucked ass. no traction ever. I reccommend a stock gsr engine with double oem head gaskets, 50-60 trim turbo, ls transmission with a 6puck clutch setup or better, fuel system and ecu tuning. crome is good bang for the buck. That setup made 308whp @ 11psi daily driven for a year and a half before i sold the car. I went 11's on slicks in an eg hatch shell with interior and all. It's not cheap to build engines today, trust me I build them for suckers every day and its like baking cookies for me. I enjoy it and i make good money doing it. I do short blocks, so PM if you want a block built. I specialize in ls-v setups, NA mainly.