Some background info and then 2 questions about the exhaust situation. I recently had my Harley-Davidson cherry popped with an awesome Ultra, acquired from a great Californian just relocated to Texas. Thanks, Adam! The Ultra's fuel injected motor is highly modified. Stage 3 I think. Screamin Eagle parts: dealer installed 95" big bore kit, performance clutch kit plus easy clutch kit, ported and polished performance heads, forged pistons, forged rocker supports, pushrods, compression releases, and roller rockers. Feuling Super oil pump and lifters, S&S gear drive on Andrews 59G drag cams, and HD racing software. She's chromed out with lots of other extras, was dyno tuned at Quaid Loma Linda Harley-Davidson, and finally, equipped with SUPER TRAPP 728 MEGAPHONE SLIP-ON MUFFLERS, slash cut, of course with their disc and end cap system. She came with the build sheet and dyno printout showing peak numbers of 95 ft lbs of torque and 102 horses. Torque is awesome at 80 ft lbs at 3250 RPM, peaking at 95 at 4250 RPM, holding steady until 5000, then dropping off slightly. Horsepower builds steadily and linear to 80 at 4500 RPM, through 6250 RPM where it peaks at 102. I can't find words to tell you how great the Harley experience is and the feeling of all that power, the rumble, the tremendous roar when I get on that throttle, the vibration, the welcome to The Family I experienced from all my new friends and brothers at the local watering hole, all made a believer out of me. I got myself my first tattoo, the bar and shield logo with a skull meaning "for life." My Harley is so much more than a motorcycle, the experience far beyond that of the many rice burners I've always ridden. I'm blown away and glad I finally pulled the Harley-Davidson trigger and took the plunge. This is one fine machine and no problems whatsoever after months of riding and lots of miles with my beautiful wife on there all the way! She loves our Ultra too.
My questions are:
(1) Why does the header pipe on the rear cylinder appear to split or "Y" into two pipes, one going to the rear slip-on megaphone muffler on the left side, and the other looking like it joins the front cylinder exhaust pipe before that one goes into the right side slip-on? Is the rear cylinder exhaust header pipe really dividing into two pipes? The front header is definitely a single pipe. Is one of these at the rear cylinder "Y" a dummy pipe for appearance? Or does the right muffler do double duty while the left one gets off easy?
(2) The left megaphone appears to have fewer discs than the right. Both have identical chrome Super Trapp end caps. Sure looks like the right muffler has more discs as that stack definitely extends further from the end of the megaphone. Also, the right side end cap develops a yellowish discoloration that the left side does not. It cleans off but seems like it's getting harder to remove as the miles add up. Makes the right cap look dirty while the left stays shiny. Is this the correct setup with fewer discs on the left? Maybe because the left muffler really does have less exhaust gas going thru because the "Y" does send more to the right? This seems strange to me but I have no intention of changing anything unless I call Super Trapp and ask their tech what's going on and get definite info I can trust. Seems like she might be running rich sometimes. I can smell richness in the exhaust when the motor is cold and the left exhaust discs are building up some black residue. The right side discs are much less black. Could be worn out muffler packing involvement? She is 18 years old, but has only 34K miles. This old girl has been babied too. I'm taking good care of her, no abuse whatsoever. I take it easy. Got all that road burning and footpeg dragging curve carving out of my system years ago.
I thought I'd check with my bros here first and start to build a consensus. The bike really runs great, performs so well I can't believe it, and sounds fantastic. No issues for months now despite all the naysayers! It took me a long time to research the right Harley to own, to get past all the negative stories and bad press about Harley and The Motor Company. Took even longer to decide which model fit my style with all the best features I wanted, at the right price, and then even longer still for the right Ultra to appear in Dallas for sale. All the stars aligned one day and BAM! I'm a proud and happy Harley-Davidson owner at last!
These minor issues are no big deal but I know this makes for interesting brainstorming here on The Harley-Davidson Forums. Thanks for your interest and input. God bless and ride safe!

 

1. Back in the 1960s IIRC BSA discovered that adding a balance pipe between the pipes on their twins improved torque. Before long every other brand on the planet who made twins, of any sort, was doing the same. On their dressers Harley came up with that odd set-up you ask about, but it has the same benefit. So the answer is: better performance.
2. That odd set-up described above means that the flow of exhaust gasses out of each muffler is different, so to optimise performance the baffles in each muffler are 'balanced'. Stock mufflers also have different baffling.
3. Don't take things too easy! Give the old girl her head on occasions, to ensure the exhaust gets baking hot right through. That may help to burn off those deposits. The red line on your tach is there for a good reason - make good use of it!

 

I agree with the above. Looks like who ever owned the bike previously took pains to balance the exhaust. Otherwise the right hand pipe flows noticeably more than the left hand pipe. If you look underneath the cross over / balance pipe is rather small and on stock headers a bit flattened.

I think the supertrapp system is pretty good as it permits the tuning of the exhaust if you wish.

 

Thank you Sir Graham and Miner for the info and advice. I'll definitely take it seriously and do it. I like the quote from Tertullian especially, golden words of wisdom. This HD Forums is a gold mine of great advice! I'm not inclined to mess around with anything on the setup because it's dyno'd to the maximum possible performance just as she sits. I can't imagine I could improve things with seat of the pants experiments. She pulls away from everything from a standing start at stoplights, even loaded two up, and I'm not even accelerating hard! Torque is astounding. The power curve is right there, at low RPM, which is exactly where us street riders want it. Just about all the work, time, parts, and expense have been put into "Heather" and I'd be a fool to screw her up. One more question: Think I ought to unscrew the discs on the Super Trapp megaphones and clean them? I learned long ago that leaving well enough alone is usually the best path to take. Wrenching on old exhaust components, to me, would probably result in sheared off screw heads, stripped threads, or worse. Thanks again, guys, for your words of wisdom!

 

Probably as Graham has noted, just give the bike a good highway run and see if that will burn off the carbon. A good high speed run is good to do (in my opinion) every so often especially if you have done a lot of city driving. Maybe the Cat is gone and the pipes don't get as hot as they might otherwise? If just a soot coating I wouldn't worry about it.

I have similar mufflers (SE fat shots) which I think are made by Supertrapp for Harley. They have some black soot on them but I don't worry about it. They sound good to me without being irritatiing. On a long ride loud gets to be real wearing (had enough loud in my life).

I would like to find a plug for the cross over and just run my system as a 2:1 exhaust system. If I can find a plug it might be a cheap way to gain some performance? The 2:1 systems seem to always have better performance numbers.

 

Here are pictures of my exhaust outlets.

 

No cats in 02, you have the stock head pipe with supertrapp slip ons...so no crossover under the bike either. Like you said yourself...someone else spent the money and time to dial the bike in right. Now it's up to you to ride the wheels off. If ain't broke don't fix it.

 

Thanks Mr. Beagle for your comments. Yes, sir! you are right. I'm enjoying the hell out of this fantastic Ultra. I'm blessed, lucky, and thankful. And I KNOW it. I was riding her tonight, and what a ride! Super motorcycle. I'm not touching a thing on this Harley. Just keeping her running with 3000 mile oil changes and check ups. Thanks again for your input, sir. God bless you.

 

If those mufflers have been on the bike for any length of time I suspect you may have problems removing those screws. They are very long and not very large in diameter and it may be worth simply leaving well alone! I have a SuperTrapp 2-into-1 on my bike (see sig pic), which I installed in 2008 and I've already given up trying to get my screws out! By all means use a variety of cleaners and brushes to spruce the tips up - perhaps some heat-proof black paint on the caps? Having suggested that I'll now have to go and take a look at mine....