The noise is of little concern compared to how harsh they are on the open road. Anything more than an inch and a half or so of travel and they are nothing short of brutal on a bumpy road at highway speed. I sold mine after my head hit the ceiling a few times and almost hurt my back on our local highways.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)