Which Rear Subframe Bushings should I buy? (5 MT X5)
 

I've been in need of rear sub frame bushings for a while. The manuals seem to chew them up pretty bad, These were toast before I got The Black One at 158K miles. I plan on taking this thing past 250K (maybe 300K+) so I don't want to be replacing them in another 50-100K miles.

There's a big price difference between the aftermarket and the OEM bushings. But I saw that polyurethane bushings are being made too. ECS tuning wants like $500 for a set of polyurethane bushings, but I saw that amazon has them for half the price.

Has anyone replaced these with polyurethane? Will it be worth putting them in over the OEM replacements? Any thoughts are appreciated.