We had a leak in the intake side, but our biggest leaks were on the exhaust side. But neither of those were the rev. issue. One of the things we tried to fix the rev issue was moving the turbo and completely replacing the exhaust system. Since that didn't fix the problem, any leaks that subsequently developed weren't likely to be the cause. We're setting records at 10K RPMs, so I'm at the point of just not worrying about it nay more.