its the 5.7 hemi

 

I have a 50 series (single) on an 08 Hemi, sounds great. Still have resnator but plan on taking it off at some point.

 

On my truck, it came with a 70 series big block. It isn't by any means loud, but you can hear it some in the cab, and people know when I take off. However, I plan upon taking it off, and doing something different with my exhaust.