I just bought a used Greddy SP. When I move it around, I can hear things moving around inside the muffler (when i'm hearing it, i picture rocks moving around, but i know its not rocks its something alot lighter. I'm assume it's loose particles (maybe fiberglass..) thats suppose to absort the sound. I was just wondering if any experience this and does this effect the sound when installed? (btw, no matter how much i shake it, it wont come out)
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It's not going to hurt your car in any way if it's hooked up. maybe try to flush it out.