Powerflex are a good alternative to OEM, they're much easier to install and firm up the car a little bit. Make sure you grease them well with the included grease, and they'll last a while with no squeaking.
On a side note, I ran Powerflex bushings for a few years but have recently (last 20-30k miles) switched to AKG bushings. They're much firmer, and unless you use the proper grease they squeak, but they last forever. I usually only got about 40-50k miles out of a set of Powerflex control arm bushings.
Final note - use E36 M3 bushings. They're the same diameter, but centered (rather than the slight eccentric on the XI bushings), so they're much easier to install correctly. You may need an alignment afterwards, but it will still align close to factory specs.
- 10.5:1, PB N31 cammed M30B35, Miller WAR and MAF, style 29's and style 5's, urethane everywhere, revalved Bilsteins
500/450 Coilovers, Vorshlag camber plates, UUC SSK, Mason Eng. strut bars
Hella H1/H4's, Schroth Rallye 3's, Dinan 25/19 sways, e32 750i brakes, Bav Auto headers, M5 clutch and FW
Last edited by athayer187; 11-08-2012 at 11:48 AM.