I have the SLS side and front on my P5 with 85k miles (maybe 86k now.. I'm afraid to check) and everything is peachy :)

So you still have your original stock (busted I assume) rear mount?

yes it is needed, if it wasn't mazda wouldnt have put one on it. depending on how bad it is u might not need to replace it. how do u know the rear is shot? you cant see it without taking stuff off

I didn't mean "needed" as in should I remove, I meant would I have to replace it. I don't for sure which of them are actually shot, but I do know that I have a lot of drivetrain slop.

if ur stock and the rear isnt completely obliterated it should be fine.

Yeah chances are your front one is torn and that is causing the drivetrain slop you are experiencing.

Try doing the front (easy) and the sides first. If it still hops like mad or seems sloppy - then bite the bullet and do the rear. I would use diesel Protege mounts (littel stronger than stock - but not 'harsh' like the AWRs... My $.02 worth...

I think I might take that route, cuz I really don't want any more vibrating and harshness than what's already there. Where do I buy those mounts?

AWR side inserts @ protegegarage.com -$45 shipped.
SLS front motor mount @ slsperformance.com - $68 + shipping, might try the discount code M247-10 for $10 off, but it may have expired by now.

You're rear mount is probably ok. I'm at 60K and mine's in good shape.

SLS only makes the front and passenger side mounts. If you want to use their driver side mount, you'll have to wait until they're finished developing it.

If your side mounts aren't too bad you can install AWR inserts to firm things up--they should only increase NVH nominally.

Here's an interesting occurrence--this guy's atx protege had an SLS side mount bracket failure. SLS seems like a good company--I'm sure they'll address the issue.

sucks.. I'm sure they'll fix it and address the problem if there is one though. That's the first I've seen of the side mount having any issue aside from the couple that were let out with the prototype brackets (that bent piece was just two welded pieces in the prototype). I'll have to make sure mine is all bolted up properly still :)