I also go to tunehouse and have pretty much the same power as you! Has dropped off a bit because valve springs haven't been done yet, getting them done and retuned on wednesday. I was also interested in the GTX turbo, but I've talked with Tony about it and a built tailshaft is almost definitely needed with 400+. Also MAY have to look at built gearbox, which is very expensive as I'm sure you know. Will also need the cat-back done for more power than we have now. Wish it was as simple as chucking the new turbo in ! haha