For a custom setup why bother buying an ECU from HPF? Your better of running a Vipec so you can control everything and program it yourself.
A 0.68A/R rear is too small for an S54. I ran an 0.82A/R on a GT35 and that was still too small. If you bring boost on too soon you will break ring lands with more than 10 psi in a short time period. If you look at all the HPF cars with stock engines boost comes on after 5000rpm. That's how they keep them living. Would feel lazy though.
Just buy a HPF plenum. They are well made, fit well and work. Don't even bother with trying to use the stock plenum.
Don't look at the power American cars make on US dynos. You won't make anything near what they make. Aim for around the 400rwhp and you will have it last a while with boost coming on early. If you want to run more boost make sure it only starts coming on boost after 5000rpm which to do you will need a big A/R rear maybe a 1.00A/R or bigger. Or go a bigger turbo around a 800hp rated turbo with a 0.96A/R rear. Then you will most likely see it living with 450+rwhp but it will be lazy coming on boost more like a supercharger.
BMW E46 M3 Turbo 570rwhp @18psi (old setup)
BMW E46 M3 LSX 427ci 800hp N/A
Ultima GTR LSX 440ci 800hp N/A
VY SS Ute Turbo 1004.6rwhp @ 28psi E85
Ford Escort Mk2 2JZGTE 600rwhp @14 psi
04 Yamaha R1 154.3rwhp
ISUZU FZR550 tilt tray (GT35 Turbo)
Last edited by 02PRUV; 02-22-2012 at 04:23 PM.