Well i had the turn downs installed for like 10.00 more. Maybe its the mufflers, i had a 5.0 before and it sounded louder. I think the muffelrs are ttwo chamber or three chamber or something, cause its not that loud for having no cats, shorties, h pipe.With turn downs, the ground tends to absorb some of the sound. However, there's nothing like cranking it up next to someone who has a sensitive car alarm...really a ground pounder. Plus it does tend to kick up dust since they're basically against the ground (which can be a cool effect). I've had both and really don't notice a huge difference, besides the effects previously mentioned. Are they charging more for turndowns?