There are many muffler, lots, (based on engine size, sure)
Cat back (sorry )) means from the CAT back, this means the NON EPA controlled, end. or even DIY
but the technology is as follows.
glass packs, most ive used are polar, IN and OUT, if you look inside, the bent flaps in the tube, inside, those Front > rear, see how that V edged catches the sounds.
baffle muff. its just baffles and most are polar, some even have up and down for water drains, (fuel burns to H20 and CO2) wiki mufflers its all there.
a pure sonic muffler, used sound echo cancelling tech. (they are like magic, wiki it.)
the turbo muffs are just high flow, and more rugged.
you want a muffler to spin around smoothly? Ive no idea what that means.
Koyo bearings are all good
counterfeit not.
clones not. (no names called , like "Som Ting Wong")
id call rock and complain,, never got a part from them bad, ever, and used them since they opened there doors.
do not buy those listings on rock, close out specials. you might get who knows.
if worried, call them and tell them what you see there and ask what it really is.
id not do any off this.
every store in town here, can buy or sells bearings.. if not the cars will stop rolling for sure. (one way we won WW2 is bombing bearing factories... for just this reason)
rock sells very few koyo
if you google site search them, i see almost nothing
i see right now, KOYO differential , bearing kit and nothing else
you should post a link to the bad bearings. or was this 10 years ago, and memory fads.
here is this site search
https://www.google.com/#q=koyo+bearings+...ckauto.com
wish you would show links so we dont have to guess, car and what bearing is bad in car.
