If you are going to go ahead and do dual exhaust, I would recommend that. Also, keep in mind that the XTerra comes with the potential to do TRUE dual exhaust coming out of the engine. Take it to a shop that won't charge you for looking at it and ask them if they think they can do TRUE duals for you. Me personally, I think dual exhaust on the XTerra looks good, but mainly for show. If you are gonna be hopping rocks, it isn't practical as the piping might get damaged. However, if you just wanna hot rod it, then go ahead.

-Seph