Going to start building my car looking for input

[RETed]

Okay, you can use most of the A'PEXi exhaust, but you need to hack the front part of it off.
Like I said before, it's a 65mm flange in front to mate with the stock catalyic converter (exit).
65mm is smaller than 3".
With the GT35R, a 3" exhaust is recommended minimum.

Fuel injectors...
1600's used to be popular, but I haven't seen them recently?
Anyone can help with this?
The Haltech has no problem firing 550 stock primaries and 1600 secondaries.
550 + 1600 is good enough for 400 no problem.

Stock fuel rails not a problem.
They will handle 400 no problem.
You'd need to worry if you're going for 500.
If you're looking for something to modify, you can convert the rail to parallel flow and run an aftermarket FPR like SX or Aeromotive.
http://fc3spro.com/TECH/MODS/FUEL/fsystem.htm
This is not cheap!

Good luck and stay safe over there!


-Ted