I want to buy a set of resonated test pipes
 

I have the stillen supercharger with stillen's headers, test pipes and their cat back exhaust but I think it's too raspy. I'm looking to buy or trade for a set of new or used resonated test pipes. Any advice as to which brand will get me a deeper tone would be greatly appreciated and if anyone else has had experience swapping test pipes for a different sound please chime in. Thanks