Back in early December of last year, I'd bought Raceway URAL's (formerly Raceway Services) kit to convert my 2014 URAL Patrol from having two mufflers, to just using one, the starboard one.
You see, the stock mufflers on the sidecar rigs made by URAL have what I've come to think of as a design defect. Nothing safety related of course, it's just that when one's rig is on a rough/rocky trail and is tilted towards the left or port, the muffler sometimes contacts a protruding rock.
Said contact, given enough speed/force, tends to knock one's muffler loose from its connection to the catalyst pipe or even the header pipe. Quite a PITA to put back in place while on the trail, let me tell you! I'd taken to carrying a heat-proof glove and a big hammer for just such occasions.
As it is, even when the muffler doesn't get knocked off, it acquires some rather sad looking "dents" and scratches from rock impacts.
Reference pic, the red arrow shows where rocks usually
impact the muffler when rig is tilted to the left because
of rough terrain conditions.
The Two-into-One Header pipes from Raceway URAL allow you to eliminate using the port-side or left muffler and catalyst converter pipe, that links it to the left side header pipe, which goes into the left cylinder head.
The stock header pipes. The holes you see near
the junction of the header pipes to the cross-pipe are
the oxygen sensor "bung" holes.
The hardest part of the whole install? Removing the oxygen sensors that were rusted on solid into their mounting holes in the stock header pipes above. I eventually succeeded in removing them but basically ruined the edges of the 14mm nuts securing them into the header pipes above. Dammit.
Tried three different 14mm open end wrenches, all were just slightly loose! Ended up using vise grips and brute force after trying both solvent oil and applying heat as well. Sigh.
Once past that particular obstacle, all else went pretty much OK. I had previously purchased a "reducer" to allow for the mating of the new header pipe and the stock muffler which I elected to leave on the right side of the tug. Darrell S., a fellow Uralista, had previously done this install and had elected to use a HD Sportster muffler for his rig.
I have not, ever, had a rock impact the right side muffler in the almost six years or more that I've been driving URAL sidecar rigs, so I figure it to be a good risk.
I had to cut the right side header pipe from Raceway Ural in order to fit with existing hardware. Raceway Ural ships it to you long, so you make final adjustments as you do the install.
In the picture above, you can see the pipe onto which the left side header pipe connects.
Above pic shows the right side header pipe mounted to
right side cylinder. Again, you can see the pipe where
the left side header pipe will connect.
Now you can see the left side header pipe connected and
secured onto the right-side header pipe.
Though it was a damn close fit on both ends, I still ended up with an exhaust leak on the trailing edge of the reducer! Darrell advised using some heat resistant sealant from the local auto parts store and so it was applied.
I removed the port side muffler and mounting bracket, tightened everything down on the new assembly, took it out for a test ride and everything seems to be good to go!
Here's some pics of the final assembly:
The right side header pipe, linked now to the stock right side muffler
You can also see the Mr COB belly pan which protects
the oil pan.
The left side header pipe, mated to the right side header pipe.
You see see the right-side oxygen sensor's cable near the right-side
header pipe.
Sorry the rig looks so dirty, it gets that way when you go riding in the snow. What you're seeing is dirt-encrusted accumulations of magnesium chloride on the radiator fins of the cylinder heads.
I am quite happy with this farkle for Scarlett, she's gained about four inches of ground clearance on the left/port side of the tug. Scarlett is ready for this Spring's Moab gathering, and she won't be leaving her left side muffler on the ground this time!

just look at that new ground clearance!
Notes:
Did not use the new header gaskets provided by Raceway, re-used existing ones. Wanted to avoid removing the stock header studs after all the "fun" I had with the oxygen sensor mounting nuts. Using the Raceway gaskets, which are thicker, would have possibly required the longer studs they provide.
Update: 24JAN16. Replaced the reducer with the one pictured below that I got from O'Reilly's Auto Parts. It's always best to ensure that the flow end goes into the next section, shall we say. Previous reducer forced the flow out at the join point, no amount of sealant would do the trick.
Update: 28JAN16. Found the source of the exhaust leak:
left side cylinder head, this is the stock gasket that
came with the rig.
The defunct gasket, came apart as I removed it from
left side cylinder head, no wonder I was getting an
exhaust leak.
The right side cylinder head gasket seemed "ok" but of course was replaced with the slightly thicker gaskets that came with the new pipes from Raceway URAL. They'd also included longer head studs but the existing ones were long enough for the stock crowned nuts to grip and be tightened down.
A test ride revealed all the annoying popping and backfiring was gone!