I have on my 355 high flow primary cats, no secondary cats and a quicksilver muffler. It sounds pretty good (though rather loud) at idle and part throttle but does not have a high pitched scream at high rpm. It actually seems to get quieter now when the bypass opens. I removed the muffler and looked inside with a mirror. I made a few crude drawings based on what I could see. The pic labeled "QS original configuration". Basically the primary inlets go into the muffler and after a short perforated section dump into an open plenum. (there are internal walls separating the area around the perforated lengths and common plenum. I don't know if those outside areas are hollow or filled with packing). Exhaust gasses basically collide head-on and can then find there way through any of the 4 outlet pipes . When the bypass valve opens it too just dumps into the common plenum. I'm guessing that noise volume does not increase due to increased turbulence. 2nd picture. In this plan the 2 main inlets go to the common plenum head on and must find there way through 2 available outlet pipes. When the bypass valve opens exhaust is routed directly to the 2 remaining tips with straight solid pipe. I think this should quiet it down a bit during idle/cruise but make it dramatically louder when the bypass opens. 3rd picture is the same as the 2nd except there is a built in "X" pipe to help direct primary exhaust flow. I could also perforate the "X" and put muffler packing around it. Any input or ideas welcomed. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
