Before you pour the dough into the Turbo, get a bigger intercooler or and after-market one. Our Intercoolers suck once you get over 30 psi for cooling, just too small and don't flow enough. While your at it, upgrade all the intake lines to the 3. 5" set off of a recent model rig, maybe even the cooler.
4" sound good. I was also thinking of a partial 4" with the Walker parts, but I can't find the post with the numbers... Anyone have those handy????
How about a Scotty air system??? Its not done yet but we are working on it. . LOL
J-eh