New manifold more induction noise?

[spinmaster]

I have a SLR with PTP throttle bodies. In an effort to reduce noise I have put a techcaft silencer on.

 

Due to having a very poor manifold (4-2-1) I have just had a new manifold made (4-2-1). The car now appears quicker, but I now have a huge roar that I never had before!!

 

I this due to an improvement in the gases flowing out of the engine and allowing more air in?

 

What is the best way to reduce induction noise?

 

Looks like I will never get down to 98db!!!!