Tranny noise? Identify this sound!

[Ninjabread]

Ok, well I've installed a Centerforce stage 2 for fun.It was fine for 2 days, but now something is making a noise towards the front of my tranny. It only does it on deceleration, and revving down.

At first, I though it was my exhaust hitting the chassis due to my new solid subframe bushings changing the location of the exhaust a bit, but upon further inspection, I realized that it's coming from the rear of the motor / tranny.

The best way I can describe the noise is kinda of like a rod knock. I can also feel the vibration through the clutch pedal when it's making the noise.

I'll have a video up in a few minutes, any help is greatly appreciated.