Please note, this is the race stiffness.
Made to fit the newer generation of Impreza chassis these mounts will also fit a number of other NEWER Subaru models. To check for fitment take a look at the pics and instructions. If your Subaru has the mount with the bushings on the ends then these will fit. (Except for the old Legacy Turbo - we know they won't fit on these).
See, the problem is this - the stock bushings are just plain wimpy. First, they are made of rubber (floppy, sloppy rubber).
See, when you get on it the stock bushing flexes too much, and the void in the bushing closes quickly causing an impact. This is the source of that stupidly distracting clunk. It's also inefficient. You can also think of it this way - you're only putting out a finite amount of energy to drive the car forward. Why the heck would you want floppy, wimpy bushings soaking up some of that energy when you could be putting it to the wheels?
So what's the big deal with these?
-Urethane instead of rubber
-Stiffer than stock
-No stupid voids
-There are others on the market making replacements for the bushings. Those are all one piece designs that require a press to install. Come on, how many people have a press sitting around in their garage? Ours is a split design.
-You could get the entire STi branded part with Group N bushings, but the metal portion of the mount is the exact same as what you already have on your car.
-NVH - Hey, we've been playing with these for a while now and really haven't experienced much more NVH. Sure, there probably is some more, but quite honestly we can't really tell.
-Cost - you remember those others we mentioned above? Yeah, ours cost less.