sr20 won't rev over 4500 rpm.

[bahlorm]

Hey guys I'm stumped here. I have a red top sr20. It has a gt2781r turbo, 550cc fiveo injectors, z32 maf, and an enthalpy tuned ecu.
I had the turbo installed with a stock system before but I was experiencing fuel cut at 6k rpm. Now with the injectors, maf, and tune my car gets to 4500 rpm and backfires constantly and doesn't go any higher rpm.
So far I have sent my ecu back to enthalpy to verify my ecu was correct. Went through 2 sets of fuel injectors. Tried about 3 different mafs. Got new plugs. Ran a jumper wire from my speed sensor to the ecu in case the ecu wasn't registering my wheels were turning causing the launch control to activate. Checked for any vacuum leaks with carb cleaner and also a poor man's smoke test with a cigarette. I'm lost at what this could be.
The car idles fine, revs fine until 4500 rpm. I'm getting no codes on the ecu. Anyone have any ideas on what to check? I'm at a total loss.