Howling/Whining Noise.

[1slowdsm]

Ever since I put the new exhaust on, I've been having this howling/whining noise. It usually happens after 2500 RPMs and if normal driving it stops at about 3500 RPMs. If I'm on the gas, then it usually keeps howling and when I let of the gas or shift it'll howl down and start over again. Does anyone know what may cause this? At first I thought it was the t-case low on fluid, but I checked and added to it and did the same to the tranny but it still howls. It kinda sounds like a weak super-charger on top of the turbo....:/