So I ride literally every day, and usually get up early enough that even chickens and bats have the good sense to still be sleeping. Given that I have quite a few neighbors, I don't want to be "that super-loud biker guy who scares children and quite possibly rapes elephants".

So I figured I'd modify the stock exhaust so that it's just loud enough to be heard by the rider at speed, but not loud enough to trigger a Homeland Security emergency mobilization.

I worked slowly. For any n00bs reading this thread, the stock slip-ons for the new Wide Glide (and, presumably, 2011+ Fat Bobs) basically are a 1 1/4" pipe with a plate blocking it about one foot in from the engine (front) end of the slip-on. Basically the gases stop at this plate, exit through holes in the sides of the tube, travel through the baffling material surrounding the center pipe, and then re-enter the center pipe on the other side of the blocking plate through more holes in the sides of the tube. From there they continue their merry way to the outlet end of the slip-on where, as legend has it, they go on to pillage towns and burn down nearby Smart cars.

It is this plate which blocks the tube that I modified. The catalytic converter is, in my case, in the header pipes just before the silencers, so that wasn't an issue. Here are my results:

Drilled four 3/16" holes through the plate - Very slight increase from "quiet" to "careless whisper".


Increased the holes to four 1/4" holes through the plate - Again, only a very slight increase in loudness. From "careless whisper" to "silence of the lambs."


Added two holes to bring it up to six 1/4" holes through the plate - Loudness was increased a bit more. From "silence of the lambs" to "Ready to Rumble".


Finally I said "f**k it" and went with the MOAB 1" hole saw. Drills are for sissies anyway. This gave a big improvement, with lots of low-end rumbling bass and no annoying high pitched "why don't you take out the garbage" BS. This increased the sound greatly, though not obnoxiously, all of the way up to "turn that hippie head-banging s**t off".


The maths:
Four 3/16" holes provide 0.11 square inches of unrestricted area for the gases to bypass the baffling.
Four 1/4" holes provide 0.20 square inches.
Six 1/4" holes provide 0.29 square inches.
Drilling the crap out of the plate with a 1" hole saw provides 0.79 square inches.
If the pipe were completely unrestricted, it would provide 1.23 square inches.

Keywords: FXDWG baffle plate exhaust slip-on drill WTF quiet loud old ladies elephants

 

lol...nice write-up!

 

 

I just took a piece of rebar and a 5 lb hammer to mine. A bit caveman-like but it worked well.

 

that was poetic. well done sir

 

and to contradict your little thing about the navy, GO ARMY, BEAT NAVY!

 

I don't trust myself with hammers. Not since the great finger-smashing incident of '98.

 

Best laugh of the morning right there. You funny OJ

 

I feel a MDK coming on for the wife's pipes this weekend............. thanks for the info!

 

Nice report. Well done!