Hi! i have a DOCH ZC installed in my car. THe Rad is kind of wasted, and i have anothe one in better condition. anyways to the topic. Yesterday was a pretty hot day, and i raced my friends jetta afterschool twice, and i smoked him. After the race i dropped my other friend at his house, rite after dropping him off, my exhaust (straight pipe) started making "Puffing" noises while pressing down on the accelrator. It makes this puffing noise until about 2.5 rpms and i can feel the cars power decreasd. after 2.5 rpms the noise quickly goes away and the noise and power comes back to normal, this is all while accelerating on the gas. i dont know wats wrong, maybe its my rad maybe its overheating, but the temp gauge doesnt display that its too hot yet. can u ppls tell me wats wrong please