powerflex had solid mounts? if so yeah u will get vibration
yer first few weeks , on idle at cold, dash vibrates bit badly. Once warm doesnt. and after few weeks dies down
kept mine on for a whole 4 hours, and went back to standard. bit to harsh for me.
I love it!!!
My cat vibrated worse than it does now because the timing was out so it doesn't bother me just wanted to make sure it was ok.