Nope, Mufflers were never allowed in F-1 because it would have given a boost, and then everyone would have had to have one to be competitive. Do you know for sure that the engine has a carburetor that can be throttled, or is it a straight venturi, and just being called a "carburetor"? From the looks of the picture of 4 engines, it looks like there is something stuffed in the carburetor hole in the rear cover. Can't really tell from the angle. Greg