I have done the 3076 upgrade, with 10:1 compression ratio and E 85 on 18psi and reached 416hp. My baseline NA run was 180hp The spool difference is very noticable between the 2 turbos. If you wanted 400ho I dont think you could go past the 3071. Should have quicker spool and not fall off in the higher rpms like the greddy turbo did

 

At the ABSOLUTE MOST (with this kit) I'd maybe want to see 375hp. I think the manifold is the limiting factor here. I don't want to make a mistake on which turbo to buy.

I want fast spool, with the ability to add just a dab of top end. I was thinking the 3071 would be better because it is smaller than the 3076 but bigger than the t518z. I don't know anything about trims on the blades... so that's the main thing holding me back...

Like I said, I'm not EVER going to do the headgasket. So would the 3076 spool a lot later than the 3071? Would I be able to make a little more power with the 3071? Or would the spool time be negligable and I could make better range with the 3076?

Seems like everyone is going with the 3076...

 

your question has already been answered by a couple members now... There are only a select few of us with this upgrade.. engineer x stated it may be better for auto X or track. but the 3076 may have a little better topend. just decide... im sure the spool difference is minimal so just go with the one you want.. I think the wheels are just standard in the 3076 and 3071 so just pick either or.

gt3071 = a little faster spool (my guess is 500-1000 rpm or so)

gt3076 = slower spool, but more top end

if it were mine i would go 3076 just so if you were to upgrade anything or want more boost then it is still possible.. what5 psi goal do you have?