Yeah don't go straight piping a 3.9. I don't even like V8's straight piped. There is no tone, they're just loud. So many people think it sounds good just because it's loud but that's not the case at all IMO. A V8 with true duals: headers, hi flow cats (or no cats), and a couple nice mufflers sounds FAR better then straight pipes. It's not quite as loud but actually sounds good.

 

I have a magnaflow on my 02 with a single outlet dumped just before the rear wheel and i love it beautiful sound its loud enough not stupid loud like its not drawing heat to me i had a grandcherokee with the 5.2 and i had a 40 series flow master and it never had that clean sound it was loud but not clean and i have a buddy of mine has a 1992 and its the 3.9 and he has the 40 series and his sounded real clean answer nice i thought other was an eight cylinder at first just amazing sound