Its not that much of a difference in spool. They say it adds about 250rpms to spool, which is not even 0.001 of a second. My builder is telling me ill probably start spooling at about 3k rpms and reach full boost at about 4500-8500rpms (i stop reving wherever my power stops). But if i had a smaller engine, like a 1.8-2.0l engine, i wouldve gotten a GT3071 with a .63 ar and called it a day. But i have a f23 that has been bored out so i displace more then a regular f23.

What car are you going to put it in, because if its going in your civic as a DD i wouldnt recommend it. If you want a fast ass street car, id get a disco potato for that and call it a day. With a light car, damn near instant spool, and a lower displacement engine it would be a perfect match. But if you are going for the drag/highway racing type build the GT3071/GT3076 would work good. I just dont think the transient response on that turbo with that engine would be smooth.