I have a 2006 Screaming Eagle Ultra Classic that I just took delivery of last month. Have 1500 miles on bike at this time. I changed the original exhaust to Rinehart dual exhaust, had a Harley Davidson race tuner installed, changed the air intake to the K & N design. Results = on the dyno the bike is producing 90 HP and 91 LBS of torque at optimum RPM's. I don't really know what the bike was producing in stock form, but the bike sounds better, has more than enough
power thru all gears ( I also added a Screamin Eagle 6 speed transmission ) Also another factor which I like is when you look at the exhaust pipes to see how rich or lean its running I find it to be almost perfect. Also the heat on my leg from the cross over is less. Our local dyno company only recomends a 2 into 1 exhaust system if you really want the most you can get out of your exhaust package.

Hope this gives you a little insight.

 

True duals definitely reduce the heat that the cross over pipe produces. But they do not have/allow as much back pressure as a 2 into one exhaust. To gain more hp & tq a 2 into one system is better & does not require much if any extra tuning.

Now, do most bagger owners want that look, probably not. Most like the look of duals, whether true duals or stock. I have V&H true dual headers & V&H oval mufflers. I like the look & sound. Did I gain any siginificant hp or tq, not really.

 

I personally LOVE my true duals (V&H). Can't say alot for instant gratification since I did the PCIII USB and Screaming Eagle air cleaner kit at the same time pretty much. Rideability is greatly improved....much better response over the entire powerband (noticed quite a bit below 2k....it was a total dog there before). I know all things don't cross-over so easy BUT, I do know that greatly reduced back pressure can hurt performance on the bottom end. I did ALOT of 4 wheeling and found that (1) 3" exhaust on my Jeep (Grand Cherokee Limited, 4.5" lift, 33" TrXus tires, etc.) was alot better (down low, torque) than (2) 2.5" exhausts. On Dynojets website, they also back this up (contained in their Map Selection PDF file "The best power producing systems tend to be 2:1 full pipes".....contained in their Harley section of this PDF). I used to ride a Yamaha FJ1200, have the need for speed pretty much outta my system. With my current setup, the bike runs great and can get outta it's own way (which it couldn't stock). If I were going for as much power as possible, I'd go with what works.....for what I do and for what sound I like, the true duals are the ticket. YMMV

Paul

 

BH how much would one expect to pay for these ? I may like to put them on my RK ..

Dude

 

I hate to be a pest but just to make sure. The race tuner they sold me cant do this? I have to have a pcIII

 

I'm not an exhaust designer, or even much beyond a shade-tree mechanic, so most of what I know comes from reading and assembling basic facts that are presented with the various discussions. I've been reading and watching the true-dual discussion with some enthusiasm because there are such a wide variety of opinions and I like the idea of true duals for the looks/sound/heat issues already mentioned. Two camps seem to be: It'll kill low-end torque, or, it doesn't hurt/helps performance.

First off, I read this article by TCSTD:
https://www.hdforums.com/m_152299/tm.htm

The following section really caught my attention:
Unlike reversion waves that have no mass, exhaust gases do have mass. Since they are in motion, they also have inertia (or "momentum") as they travel outward at their comparatively slow velocity of 150 - 300 feet per second. When the gases move outward as a gas column through the exhaust pipe, a decreasing pressure area is created in the pipe behind them. It may help to think of this lower pressure area as a partial vacuum and one can visualize the vacuous lower pressure "pulling" residual exhaust gases from the combustion chamber and exhaust port. It can also help pull fresh air/fuel charge into the combustion chamber. This is inertial scavenging and it has a major effect upon engine power at low-to-mid range RPM. There are other factors that further complicate the behavior of exhaust gases. Wave harmonics, wave amplification and wave cancellation effects also play into the scheme of exhaust events. The interaction of all these variables is so abstractly complex that it is difficult to fully grasp. There does not appear to be any absolute formula that will produce the perfect exhaust design. Even super-computer designed exhaust systems must undergo dyno, track, and street testing to determine the necessary configuration for the desired results. Last but not least, the correct choices and combinations of carburetor, air cleaner, cam shaft, ignition, and exhaust used in the proper relationship to each other for the intended riding application will always produce the finest quality results.

Again, I'm not nearly fluent enough in exhaust theory to say, "this is total BS" or, "it's right on the mark", however; it seems to be well thought out and spoken from a position of authority. It also appears that there may be much more to optimization of exhaust beyond just scavenging. The larger article points out that the length and diameter of the pipe has much to do with timing and whether or not the reversion wave is even desireable. ie Anti-node = good, node = not so good.

After reading this article, I don't believe I could make a blanket statement of true duals hurt or help performance because so many other things impact the benefits of a 2-1 or scavenging system such as cam, a/c, ignition etc.. and even then, the scavenging effect seems to be limited to a specific portion of the powerband.

Hopefully my understanding of this article isn't too far off the mark. If it is, I'm not proud...I'm interested in replies that might dumb it down for me.

I don't have the RK for running low teens in the 1/4 mile, I've got a metric bike for that. So even if there is a loss in performance for a point or two, I'm probably going to be ok with that. I'm starting to lean toward the camp that says any (real or perceived) loss can be--at least partially--retrieved with a high flow a/c and tune.

There is one last interesting piece for those that say they feel more power on the highway for passing; the concept seems to have support in the larger article:
"More importantly, maximum mid-to-high RPM power will be achieved with the lowest possible backpressure. Period!" So, my inference, I suppose, is that if you feel that you've picked up some upper RPM power you probably have lowered backpressure and at least to some extent, lost some low-end torque. Again, just my interpretation