I just dumped a bunch of cash at Apex to work on my E28 M5 with a s38b36 motor. Ben is a good guy. I met him about 7 years ago through a buddy of mine that owns a BMW / Porsche dismantling shop in San Diego.
My variable intake wasn't functioning on my s38b36 since I did the conversion, so I had him hook it up properly. He also changed the water pump, welded up a crack in my oil pan, and did a valve adjustment. I plan on having him do some more work soon...so far I'd definitly recommend his shop.
-Marcus
88 M5 w/ s38b36