Here's my posts from another thread about poly mounts:
I've had em for around a year or so and like them. But I also have every rubber bushing or mount replaced with poly. The only rubber that remains are the engine mounts and transmission mounts. Never squeaks at all - and mine are even the red ones without graphite.
More like a sports car like ride than anything, driving a stock truck feel terrible now because mine doesn't have the sloppiness and body roll that comes with softer rubber.
BE WARNED! They absolutely increase in cab noise and vibrations from the road, engine and lift pumps. 20-30% at least! and take into account I had sound deadening(like $500 in materials worth) prior to installing the full poly kit too.
Someone asked if I was glad if I did the change:
Oh yeah, I personally don't mind it until something starts vibrating with a passenger in the car (door card does it occasionally). That's the only bad part, the ride I love. I can't stand being in vehicles that people describe as if you're "floating on a cloud" - to me that's a design that sacrifices handling for comfort.
CCSB, LML 20s on factory SRA's, stock height and 8300-8500LBS with me in it.