I run the ones from Intense. You would be good just replacing the lower blocks. Unless you want to be rattled outta ur seat with the upper round mounts in too. Like Sabre said above, you really only feel the vibes at stops at lights. I replaced mine about two weeks ago. I could tell an immediate difference with traction. Much better breaks on the burnouts too.
Definitely worth it.
Not a horrible pain to switch either. Just make sure you soak them Wd-40 or PB Blaster first. Much easier that way. I worked mine out of the brackets with a pair of screwdrivers. Bout a 20 min job all round.
