nasty50

so i have a90 hatch with: stock bottom end, stock heads but with big valves (2.02 intake and i forget the exaust), f303 cam, trick flow track heat intake manifold, 24lb injectors, maf, fpr, cold intake, and full exaust (headers, catless h pipe, dual chamber flows).

i have the stock tb on right now, but i have a holly 75mm tb to put on. i have been reading the forums and i didn't realize that too big of a tb could hurt performance. i can return the tb, but does anyone know if i should stick with the 75mm or step it down to a 70mm.

PX429

go the 70mm

by the way what MAF do you have?

jthorn9

Unless you go F/I, I'd step down to a 70mm TB. A larger TB won't necessarily hurt hp, but it can lower bottom end torque.

w8less

if for some reason you actually do lose hp it would be minimal. you might actually gain it back up top. i don't know if i would worry about it. if it will make you feel better i wouldn't go with less than a 70