I own a Porsche 997 C2s, It's been serviced by Kenny for 2 years now. I have found him to be extremely honest with me. There are obviously quite a few things you can do to your Porsche, exhaust, air in take, etc, etc and in many cases the shop would love you to keep spending with them but in Kenny's case he has actually told me not to waste my money with some things which is great. Kenny recently replaced my suspension and also put in a quick shift for me, the car feels amazing, it's like new!!
I think that Kenny's rates for labor and parts are really fair and inline with other service centers, Auto Werkstatt had a good vibe in the shop, the guys are always very friendly and make you feel comfortable. He also uses Porsche parts and is against after market. They also service my wife's BMW x3 and its running like a dream. All in all, I trust them and feel taken care of.