They tend to sound better when you get somewhere around 500-1000 miles on them. I got the 12580 on my 06 Pathfinder with DT shorty headers and DT mid-pipes (eliminates the rear converters) and kept the stock tailpipe and post-muffler. I definitely notice a drone during light to mid-throttle acceleration, but idle it sounds good and at wide open throttle, she sounds great! That said, I didn't notice any real gain in gas mileage nor performance with just the exhaust mods. I later added the XTP plenum spacer, aFe Momentum intake system and reprogrammed with a Superchips tuner to the 93 Octane performance tune. The biggest "noticeable" increases in performance came with XTP plenum spacer and the Superchips tuner.