Poly bushings won't be any quieter without some treatment. As they
physically rotate in their shells rather than twist there is a greatly
increased possibility of noise.
I've done a couple cars with them and it does make a nice improvement
in tightness, but at the cost of ride quality. The first two, I did
exactly according to the mfgrs. directions and used the "Gorilla Snot"
grease on the control arm bushings after roughing up the bushings to
expose the supposedly impregnated graphite in the poly. They both
creaked every time you went over a driveway apron, although they did
otherwise handle well.
The next vehicle I did, I did not have the option of using
"polygraphite" bushings only non-graphited polyurethane. Since
following the directions didn't work for me and this vehicle was
relatively easy to disassemble (VW Scirocco) I decided to
experiement. I bought a tube of powdered graphite and rubbed it into
the bushings until they turned a uniform pencil lead color before
installing - this was easy as they were molded with red-colored poly.
That car was dead quiet for tens of thousands of miles afterward until
I sold it, so I would actually recommend using that approach rather
than using grease.
The poly is much easier for a DIYer to install, as they don't require
a press, bench vise, or improvised all thread/nut/socket/washer setup
to press the pushings in, they push in with firm hand pressure. I
replaced the control arms on the Scirocco with new making the job even
easier as at the time they were about $25 apiece, which was worth it
to not have to press the old bushings out and have to derust,
straighten, repaint etc. the old control arms - just wave a spray can
at them, assemble, install, done.
just my experiences...
nate