I've got a '94TT with TRD cat-back, RM downpipe, and the FFC and free boost mod. My problem is that the car all of the sudden tonight started popping and hesitating above 5K rpm. Car still runs very strong, in fact I had just raced my wife in our 2000 Vette and walked it by too many car lengths to count. But it's definitely hesitating and popping out the exhaust. It's only got 40K miles on it and it's a 6-speed. Any ideas?