I have the YoDude setup with a dynamax muffler. It sounds great, but since I got it, the car won't rev above 4500rpm if it's not in gear. My friend asked to hear it on day so I hit the gas a little bit, then a little more and more, but when it hit 4500 the guage bounces back and forth over and over again. It makes the whole car shake like a mo-fo too, like it's about to fall apart! wtf? that can't be normal. What's the problem?