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Appendix II

Examples of Illegal Tampering

The following are examples of tampering to original equipment EPA-approved exhaust systems. Most owners who tamper with these mufflers are not content with the resultant increase in noise unless there is a straight-through passage from the muffler inlet to the outlet, i.e., a “hollow-core muffler.”

The top photo shows what the unmodified original equipment muffler for all 1983-to-present Harley-Davidson FL touring models looks like. On the bottom is the tampered-with version. Upon closer inspection, one can see straight through from the exhaust outlet to the inlet of this muffler. Note the jagged edges.

An example of tampering to Harley-Davidson’s own EPA-approved “Screamin’ Eagle” line of aftermarket mufflers for FL touring models^[1]. On the top is what the unmodified exhaust outlet end of the muffler looks like. On the bottom is the result of the owner grinding off the two small opposing weld beads (left photo), then removing the core of the muffler, sawing off protruding tubes at both ends of the core, and then reinstalling the heavily modified core. Upon closer inspection, one can see straight through from the exhaust outlet to the inlet of this muffler.

From a 2003 Yamaha YZF600. On the top is what the unmodified exhaust outlet end of the muffler looks like. On the bottom is the result of the owner grinding off the hardened rivets that secured the end cap and sawing off the last inch of the muffler. The end cap was reinstalled with common sheet-metal screws. Note the jagged edges.

From a 2001 Harley-Davidson FXST. The owner turned this original equipment muffler into a hollow-core muffler by cutting out the center and leaving a jagged, out-of-round edge.

1. This model of aftermarket muffler has a selection of different cosmetic outlet tips.