Done a bunch, never had a valve problem-my exhaust guy is 22 miles away. Make sure nothign will burn near the exit of the manifolds. I drove old black truck for months w/only a 3 ft piece coming off the engine-nothing else. Never even got a second look. Not sure what you gotta do to get pulled over around here, it sure ain't speeding or no brake lights/tailights/exhaust or driving on the wrong side of the road.