They are noisy, but they also stick like crazy. I actually have a set on my '04 PT Cruiser Turbo and last year at Buttonwillow Raceway I ran down and then was held up by a mid 1990s Nissan 300ZX Twin Turbo. My HPDE instructor thought it mighty funny that the little sports car couldn't out run the grocery getter!!

I'll say it again though...they are noisy.