noise around 1500 Rpm
 

Got my car running after the engine swap and on the first test drive around 1500 RPM with little to no load, sometimes around tip in to accelerate. I'm getting this noise, if the car had NPP, i'd say it was that opening up. But almost sounds like the exhaust goes into rapid succession bouncing off the rev limiter, but the RPMS don't change.

The car is a 2012 with a 2015 L99 engine and magnaflow exhaust.