OK, here's what happened. I got the classic engine slap "balm" whenever I would miss a downshift. So, like many other guys I went ahead and put in a solid motor mount (CPE). BUT, There was a lot more vibration at idle. I really didn't like that.
So, the last time I had to take the car to dealer, I took it off, and replaced the stock rear mount. I used a jack to support the tranny while I tightened it up. It's been a year NO MORE engine slap, Zero!!! I'm not the only one to discover this. The stock rear motor mount properly adjusted will work MUCH better than a solid mount! No slap + no vibration. Maybe the factory bolts it on - on a lift in the air without supporting the engine/tranny so it does not sit right when we get the car new?!