noisy after extractor fitted

[SSbeast]

I got pacies fitted to my LS1 4 into 1. I already had a twin 2.5inch cat back so it was a littel noisy exhaust wise already. When i got the pacies fitted it was quiter on idle and had a nice burbble on full noise and slight accelration, however the engine sounds mechanically louder now. I used to hear the tappets on slight accelration and on heavy it would dull down. Now i hear like rapid tapping on all accelration, however dosn't make the sound when in N or P and free revs. Is this normal? Cheers

[chargedvx6]

There may be a leak on one of the gaskets somewhere or it could just be the headers amplifying headnoise.