Need advice racing a 380 horse crate engine

I'm of the mind that it isn't making power. Does it make compression? Are the secondaries opening?!? You said it didn't make a difference shifting at 4700 or 5800? That should have made a HUGE difference. Like 10 MPH. Running on half a carb would explain it. So would a serious exhaust issue.

Should be able to confirm the secondaries by ear. Take off the air cleaner and floor it in 2nd gear. The "Ba-waah valve" should have opened by 3000 RPM.