I am still researching the SE103 motor and now know that the bike is a great cruiser, but not the 103 bruiser you would have if you built the 103 with the full Harley screaming eagle kit. The compression is lower; the pistons are cast, not forged; the cam is milder, not the SE 260 grind in the kit, etc. I am not saying this is bad, it really depends on the intended use of the bike. What is clear is that no matter what you do, you do want to improve the breathing and exhaling on this baby.
For the intake, everyone talks about the SE air cleaner with the K&N air cleaner. Yes, this is a proven performance enhancer, but I would recomend to everyone that they check out the Arlen Ness "Big Sucker" air cleaner setup. It is a much cleaner setup, with the head breathers incorporated in the castings, and the air entry more of a polished velocity stack. Plus is still uses any of the Harley air cleaner covers. Check the Drag Specialties book, you will see what I mean.
For the exhaust, I found that generally speaking, the 2 into 1 systems are the best from the true performance point of view, giving the best torque and horsepower, and over the entire operating range. Great systems are the Thunderheader, D&D system (won the HP shootout last year), and the SuperTrapp systems. The Hooker, SE, and Vance and Hines systems were also there. The only thing is, do you like the single exhasut look on a bagger? It would really take some getting used too, and I am leaning towards no.
So, then I fiqured the dual exhaust provides the look and symetry that looked right on the bike. I researched the Rinehart true dual system because it sounded good in concept, was a true 2 into 2, and looked really cool. However, the latest issue of Cycle World's "Power & Performance/Harley Davidson" showed a major dip in the torque curve between 2000 and 3500; coincidentily, they were dynoing these pipes on a 103 incher. This is exactly where our SERKs run the best in stock form. They were unimpressed with this system; they also checked the 2 into 2 system for the softtail, with the same results. Having read this timely article, I too was unimpressed and have scratched these from the thought process.
Finally we get to the dual exhaust using the factory head pipes; as I said, it is a compromise on power, but has the balanced look. There are a lot of slip-on replacement mufflers out there with a lot of different looks. They play with different lengths, diameters, billet ends, slash cuts, etc. I am looking for the right look with the right power. I called Vance and Hines, and they recommended their new Oval Slip-ons, saying that they flowed the best. I know there are Kerker, Python, Samson, etc products out there, and I would really like to be able to compare flow. Has anyone seen a dyno series in one of the cycle magazines that compared the different slip-on mufflers. It would really help in the decision process.
Finally of course, you will have to reprogram the computer for new fuel and ignition curves to make it run right and to take the much better breathing into account. There is Harley's Race Tuner, the Dyno-jet Power Commander, and even S&S has a system. I know that the Power Commander allows you to make changes while the bike is running, but I do not know id that is all that important. But it is also much cheaper, and there are a ton of MAPS on the internet to download and use as a starting point. Does anyone have a real reason to choose one over the other? If I buy a Power Commander for example, am I able to program more that 1 bike with it. I have 3 different fuelly bikes, can I do all 3 of them?
I will continue to research, but everyones input is certainly welcome. It is really clear that the right decisions can make a big positive difference, and an uninformed desicion can lead to disappointment. The Rinehart exhaust test clearly showed that fancy theory, looks, and name, do not always quarantee results. The right combo is out there, lets find it.
