Originally Posted by GT2871RBLUBIRD

i will speak from my build becuase its basicly what you are looking for, altho i do have over 14k in my motor, so my build might be a little more extensive than yours but:



im running the GT2871R with .86 AR 264\264 i could go on forever but basicly im running what you are looking to run and im also running it on stock level 8.5psi for break in.

ANYHOW my motor made 238whp 235wtq at 8.5psi (about 270 crank)

i get positive boost around 1200-1500rpm and full boost around 3k-3.5k

the differences the .86ar is definitly worth it, like i said i made 238whp and 235wtq and was only taken to 6200 rpm on the dyno could have gone to stock rpm level around 7500 however didnt...but the power was still climbing so i wanna say at around stock rpm level the motor probably would have made more like 258whp and 254wtq at stock boost level.

i will tell you even at the stock level the powerband is a complete BEAST, the powerband is extremely smoothe the boost transition is SEEMLESS not that ON\OFF boost, its seemless transition

stock power levels are around 184whp i made 238whp which is a difference of 54whp from JUST being built! which is completely sick, and like i said it was still; climbing so i could have probably gotten another 20whp easy if reved higher so it actually makes more like 74whp gain.

and my motor is also build to go out of the stock rpm range, altho i wouldnt probably take it farther than 8k which could be the difference from 258whp to 270whp, but those are the kinda numbers you are looking at with a built motor.... and tuning tuning is what will make you great power, but it all comes at a cost building motor and building them corretly isnt cheap at all and takes a great deal of knowledge.