just upped my spec from 400hp, i was running
L8 ecu
t34.63
siemens 55s
500 cooler
044 fuel pump
ABO7 inlet cam
free flow s/s exhaust
k&n cone filter
would go with a t38 over the t34 400hp on a t34 is really working the turbo flat out
if your going siemens 55s i have some for sale in the parts section these work fine with a t38 at 400hp could even go a little more if you wanted.
if you have the money to do it i would go 200 block longstudded for reliability with pocketed pistons
what ever spec you go for get a live map so its set up to your car
with 400hp 2wd i hope you can drive lol