My current setup is as follows:
1999 Subaru Impreza 2.5RS with a 2000 RS rear LSD.
ACT 12 pound flywheel, Exedy clutch, STI Transmission mount, Whiteline polyurethane rear differential bushings. Also STI short throw shifter with polyurethane bushings.

The stock car, and the car after all the mods listed above, jerked significantly on/off throttle (previous mods didn't seem to change that too much). I am told that this is an intrinsic property of all wheel drive systems, but if it is, its a very annoying one; a messed up shift, or going on/off throttle in low gears will make the car buck annoyingly.
So I installed the STI engine mounts as the final step in my driveline upgrades. I paid a shop to do it; 1.5hours of labor, $86 w/tax.
First impression: Unlike what others have stated, there was NO NOTICEABLE INCREASE IN CABIN NOISE/VIBRATION WHATSOEVER. I do have a somewhat loud exhaust though (Borla Headers/Catback, Random Tech Cat, Magnaflow resonator).
On/off throttle jerking was greatly decreased. I can still make the car jerk / buck if I really want to (say, by pulsating the gas pedal), but the amplitude of the jerking and the number of cycles it goes through before it stops has dropped dramatically. Throttle response feels a lot more instant. Overall I would say that I am very satisfied with it and would highly recommend it to anyone. Right now I am considering the STI pitch stop, though someone at Cobb (I think it was Cobb) told me they didn't see any difference with it installed. Any comments?

Also, I'm still getting a clunking sound from the back of my car. I don't believe its the exhaust or rear diff.; I think it may be the struts since the car makes some noise when I go over bumps too. I didn't expect the engine mounts to fix this, but if someone could have a look at the thread (http://forums.nasioc.com/forums/showthread.php?t=722904) and maybe offer some more advice I'd be grateful :)

That's awesome.... I asked a dealership about it, just out of curiosity. They wanted just under $400 to put in the mounts, 4hrs of labor. I told him I could do it myself and break every tool I owned and it still wouldn't cost that much. Guess I need to get around to doing that.

I did install the pitch stop and tranny mount.... there was a noticeable decrease in the amount of bucking from the engine while downshifting and engine braking. For $50 bucks, why not?

I might do the pitch stop; like you said; its cheap, and easy to install. The tranny mount improved some shifter feel for me, but didn't do much for the bucking. Same with the whiteline bushings; they eliminated the bang from the back on hard shifts, but didn't help the banging. Those did add a lot of vibration to the cabin, but only when the engine is stalling at low RPMs.
I just drove the car some more after posting this and I stand by my conclusion that it has vastly improved responsiveness, decreased the buckling and not added any cabin noise whatsoever. I regret not having done it earlier.
Question: The metal plate that came with the mount would not fit; the shop ended up using the stock RS plate has anyone else experienced it?

I'm not overly familiar with that model, but would the STi tranny mount fit? I think you'd see more of a change with that instead of the pitchstop.

I'm not overly familiar with that model, but would the STi tranny mount fit? I think you'd see more of a change with that instead of the pitchstop.

If you read my post you'd see I already have the tranny mount. I didn't think it made that much of a difference.

skip the pitch mount unless your car has high miles

the tranny mount makes a huge difference in how the car shifts and feels overall when you are really getting on it.

I just installed tranny, engine, and pitch.....wow, like everyone says, it is just so much tighter.....i did the install myself......the engine mounts were kind of a pain, especially the passenger side mount......but well worth it

No mention has been made as to whether STi vs.Group-N STi were used. There is a world of difference in >NVH w/ Group-N

No mention has been made as to whether STi vs.Group-N STi were used. There is a world of difference in >NVH w/ Group-N
See, this is the kind of thing that drives me nuts about this topic. Is there really a difference between what vendors are calling 'STi mounts' and Group-N mounts? After my experience with a so-called STi transmission mount in my RS, I have an extremely hard time believing that anyone who installed a set of these mounts didn't notice a HUGE difference in NVH. Mine was in my car for six months before I couldn't stand listening to the tranny gears spinning through the floorboards anymore, so I removed it. It sounded like it was bolted to the chassis using a solid steel mount instead of hard rubber.

I very much want a set of mounts in my car that are firmer than the stockers. If someone knows for sure if there is a difference between these upgraded mounts, I'd love to hear about it.

FWIW Both mounts I bought were supposed to be group N...
After driving 1000 miles with the mounts I have the following additions to make:
1- The car shifts better too. It will go into 1st gear with less grinding.
2- PERHAPS there is slightly more vibration on my steering wheel at speed. Its so mild that I can't tell. The only time I experience vibration inside the car with these mounts is when shutting off the engine.

grp n is stiffer than plain sti.

plain sti is same stiffness as wrx.

So what, it's all in your head?

Does anyone have an install page for the engine mounts?

grp n is stiffer than plain sti.

plain sti is same stiffness as wrx.
But aren't the stock WRX mounts the same as the stock RS mounts?

the point i am making is that if you want stiffer mounts, then you MUST GET GROUP N RATED MOUNTS. nobody really buys just plain "sti" mounts, because they wouldn't be an "upgrade," only a replacement. all group n mounts are sti, but not all sti are group n.

the bottome line is that when you want to get stiffer, upgraded mounts, it would behoove you to make sure before you finalize the order that they are GROUP N MOUNTS.

btw, there are also grp n top hats for the struts, and other bushes throughout the car.

If you want to make a harder Tranny Mount just make to holes from top to bottom on the mount and put to big bolts with nuts all the way thru. It works!

Does anyone have an install page for the engine mounts?
I found install instructions at the scoobymods site. When doing the engine mounts pay attention to how you pulled the mounts out. First time I did this mod it took me forever to figure out how to get the new mounts in. Second time it was a breeze because I paid attention to how the old ones came out.

I highly recommend this mod unless you're a wuss and expect sports cars to be quiet. ;) It does increase NVH but not terribly much.