rich, you have 5 and 1/2 inchs from one side to the other of the cowl on the inside where the head of the engine is i would like to find out the width of that muffler i think that would work with the engine mounted inverted do you know when it will be available for purchase take care mike, also i checked robarts web page and they are still down i will look later on today to see if i can find the exact part number for you