From a drivability standpoint, not much; but it did seem to be transmitting a bit of noise (a wee rattle actually) from that side of the engine bay. At first, I thought it might be something loose in the tensioners or the mounts for the AC, power steering, etc. Once I got in there and looked at the mount, it was fairly obvious. I did think though that by going to the poly mount first that it might have thrown a bit more pressure on the front mount causing it to be a bit noiser than it would have been with a new stock upper mount. Frankly, the only reason I decided to look was becuase I had just replaced the upper mount and thought it would be good to check out the others. By the way, I also did the lower mount while I was`at it. Wasn't that much money and now I don't have to worry about them at all.