Just what it says. I got an SCT x-calibrator and installed last night. I put about 50 miles on the car now and it seems hella quiet. I have stock manifolds, o/r mac h-pipe and mac catback. I guess it's just not backfiring anymore and I think it's more quiet, but when I accelerate throught the gears, it just seems like it's not as loud. Am I crazy or does the bump in timing smooth the power out and quiet the exhaust tone??? The car is smoother and faster through all RPMs now.