Installation Time: Less than 1 Hour
April 02, 2019
Well-made but sound required more work
Installation went fine - fit is tight, but is perfect with no trimming on the 4-door. Some have complained about weak clamps, but I thought they were fine - plenty beefy and held up well to an impact wrench. Maybe they have updated since other reviews - the muffler in my system was painted black - still stainless, but not the same finish as in the picture.
On first start, it sounded really good - louder than I expected based on views of many videos, but not completely obnoxious...but it went downhill from there. Horrible drone at various RPMs including 1500-1900 which is where I spend a lot of time. I contemplated replacing with a stock muffler, but opted for a resonator (Flowmaster 15150S, not presently sold by XT) that per Holley is made for the HP-2 which is what the JK American Thunder includes. I cut a piece out of the straight portion of the over-axle pipe and inserted the resonator with a couple of heavy clamps from local auto parts store - Holley states it can be installed before or after the muffler and this approach allows me to pick either option - I went with after. Drone is now non-existent, and I'm left with a milder, rumbling idle and a reasonable mild-moderate tone on acceleration.
Would I do it again? No - had I known it would cost $600 with the resonator being necessary to make things acceptable, I'd have likely opted to replace the rusted out stock muffler with a new stock muffler. That said, I'm pleased with the end result. Even with the resonator (very small profile) it's still a high-tuck system, it is a solid build and I do like the sound better than stock. Just not $600 better. My ratings are for the cat back only - with the resonator I would up the loudness and exhaust note to 4 stars each.
Note - don't waste time trying to wrench the bolts off of your old setup - a metal cutting wheel on a mini-grinder makes the full removal a 20 minute job - cut the nut off the rear clamp, and since you can't reach the nut on the front clamp, I just cut the band. Hangers are fairly easily removed with PB and a medium pry bar and steady pressure...just find the right angle to get leverage.