Well now that the new motor is in the car is real loud and raspy, not just at WOT but at part throttle. I was considering one of these approaches at quieting/smoothing the exhaust.
How noticably did it quiet it down?
Another alternative is putting Hi flow cats on but that is pretty expensive.
My exhaust setup consists of Hooker 1 5/8 headers, no cats, custom 2 1/2" y pipe to my 3" Borla cat back.

Also Where would I put the inserts? just in a straight section of the exhaust? Do you think that It would be better to get one in the 3" intermediate pipe, or get 2 2 1/2" ones in the pipes before it goes into the Y. Thanks in advance for your help, I just need to find some ways of quieting this baby down, Im going to a smooth but agressive rumble.