I'd personally use Karl if I was going to build another RST. They guy talks sense, knows how things works and WHY they work. Not just bolt on tuning. I'd also be confident in his workmanship and honesty. the guy makes his own heads and doesn't let anyone else do any of the work.

IMO If you don't trust the person your handing the money over, don't hand the money over. If I said Karl I want a 400bhp cvh if he said he could do it, I'd trust that he would deliver.

The only other person I'd go to would be Stu.

Though the day I build another RST is the day hell freezes over (or I win the lottery)