Well, I know I'm not the smartest when it comes to Hondas but I'm sure not stupid and this one has stumped me for sure.
My fiance has a 99 Civic Si with a short ram and a welded on muffler. Just after she got the muffler welded on, you can accelerate and the car will make an almost make backfire sound, but very muffled. It will " backfire " probably 4-5 times from 4000 to 7000 rpm. Heres the thing that stumps me. There is no power loss to the vehicle. It doesnt lose power at the " backfire " points, and it doesnt jerk. It sounds like the " backfire "is coming from the engine bay. I also can feel the re-percussions ( sp? ) of the " backfire " in the pedals while driving it. Does anyone have any idea WTF is going on here? Any help is greatly appreciated.