Did they explain to you that aftermarket camshafts will make the turbo spool later, moving the power band further up the rev range? Its only useful if you plan for well over 400kw imo and losing midrange sucks.
At the end of the day a built auto wont handle much beyond 300, do you have the coin for a Getrag conversion?
The stock manifold wont support that sort of power either so I guess you are looking at twins? You will have to ditch the Attessa which makes that much power useless for the street.
I also have doubts the 2.5 will fit on the 3.5 block without first modifying the head chamber as the pistons are much larger, besides the 3.5 heads will flow much more than the 2.5 ones ever will, you just hit the actuaton brick wall and without the cam actuation the engine is very lethargic (as you may have already found out.)
Quote: turning the seemingly impossible into reality.
So what is it they have done for you? I can understand you want to keep it to yourself as you would be paying through the nose for the workshop to learn the engine's characteristics, but it doesnt help the Stagea community to keep secrets now does it. After all, this forum IS the aftermarket support for this platform.
Please dont take this as a personal attack, I only want you to know the path you're choosing may be a long and costly one.