I got tired of the pile of crap known as a Speedwerx slip-on on my bike. It's had various issues since day one, but recently the case started spider cracking and I decided enough was enough.
Looking at the stock exhaust I realized that the head pipes(roughly 1-1/2 or 1-5/8) are knecked down into a single tube of the same size at the Y. - Obviously, that's a fairly signifigant restriction, thus I decided altering that and a custom muffler was in order to suit me.
I cut the Y aprroximately 1" up from the outlet tube, fitting it perfectly to a section of 2-1/4 exhaust tubing I ovaled one end of in the bench vise.
I then used some sections of a 2-1/4 mandrel bend to mirror the route of the stock outlet pipe, where it turns out past the frame. - I actually used a couple pieces weld together, as everything I used in this build was stuff I had laying around.
Modified the stock heat shield to fit over it:
Y pipe installed back on bike:
I fired it at this point, just to get an idea of the difference. - Drastic
difference in tone vs the open stock Y pipe, a lot more mellow and throaty.
I then proceeded to built my own chamber muffler. Since I do a lot of mud & water riding, I didn't want to deal with packing of any kind, but at the same time I wanted to stick with the hi-flow capabilities of a straight-through design muffler, but I also wanted it reasonably quiet.
I started with a 17" section of 4" exhaust pipe and two Vance&Hines 1-3/4" louvered baffles(from one of their harley systems) . I split the 4" tube in half and welded a 3" section of sheet metal in one side(will do the other after the core is complete), giving me a 4x7 oval case. Using the partial case as a template I cut five(5) end caps/chamber walls. I cut holes to fit the baffles in the three internal chamber walls and welded them together. As the pic shows, I ran one straight across the top, the other starting at the bottom and running diagonally to the top(left side is entry, right side is exit, top & bottom as seen). The muffler entry & exit will be at the bottom.
with it in the case - once the end caps are welded on it makes 4 seperate chambers.
I welded another section of 2-1/4" madrel bend on the inlet to the muffler, along with a short section of straight 2-1/4" ID tubing to allow me to slip fit it over the new y-pipe outlet. I welded two tabs on the top and bolted the OE pins on to slide into the mounting hanger. - The slip connection is secured with a SS t-bolt clamp, but I may weld the OE wire tabs on and hook the tension springs on as well since the muffler still utilizes the OE slide pin mounts and isn't directly bolted on anywhere.
I used two 90* sections of mandrel bend on the outlet side, snorkeling it to just below the rear rack. I put a couple triangle cut sections of .090 plate top and bottom to support the snorkel; also drilled a few holes in them to make it look more "finished". I then painted it with 1300* VHT flat-black header paint.
Finished muffler on the ground -
On the bike(I had ran out of paint at this point, it's finished now):
I'm super happy with the end result. It looks good on the bike and the sound is awesome! Really deep/throaty tone, pretty quiet when cruising but sounds mean under acceleration.
***The big plus*** So far I've added a tad over 15% more fuel to it through-out the map and it's still not enough, so obviously the stock Y pipe was a fairly signifigant restriction. The bike was strong before, it's getting to be pure evil now!