Whelp, I just installed the corksport inserts and here is my review:
There is an increase in vibrations, don't let someone tell you there isn't. Very little, but its there. Primarily in startup and if you ever lug the motor in rpm's, you'll notice. My wife has seemed to notice it but I have a feeling it was only after I had pointed it out.
Installation was pretty straight forward after you figured out what was what. The 3 bolt bracket is a must to remove. I also recommend an impact gun for removal. Not a simple task by hand, but doable I suppose.
All in all the car does feel more planted and solid. I would say it is worth the $40 and the time. It almost makes driving the car hard feel as though you're really not being as hard on it. Shifts are easier, motor is a bit more responsive.
Werd.