I just bought an 08 4 door hemi.I was asking the man at parts what i can do to my exhaust without voiding my warranty and he told me as long as it is behind the cats im fine.Any suggestions for good sound and increased horse power would be appreciated.

 

Do a search, there are a ton of threads on this, also check the most commonly discussed topics at the top.

Magnaflow and Flowmaster are the most popular.

You void the warranty only on what you take off/change. If you cat back, from the cat back is void. If you do a muffler, the muffler and back is void. if you do headers, the headers back is void.