mine ran 7.56:1 on a t34 .63 at 34psi peak and the difference from its previous stg1 engine? (completely std engine on stg1 chip,exhaust and air filter) was that it felt......................the bloody same off boost!i THINK the turbo spooled all of a couple of hundred rpm later,the only REAL difference in them was the MASSIVE bang the turbo gave when it came in on the 400bhp spec,other than that it was just as good around town etc...and had a FAR larger power band than my curreent NA e36 bmw 325i!