I'm maybe half way there, with the 95" kit, duals w/SE slipons, and low restriction intake, HD spec re-tune for higher redline, I don't have any head work or cams.
I would NOT be happy with any significant decrease in cruise mode gas mileage.
I have actually considered SuperTrapp slip fits if I thought I could slightly soften the peaks of the exhaust note without hurting performance, I'm not wanting it quiet, but the very peaks of the POP! part of the exhaust note could be taken down a little and I wouldn't miss it.
Hard to spend $500 for such a minor change tho.'
Ok.... few things...
You have a 95" kit.
A wiser man than I once said, "There's no substitute for cubic inches". Adding cubic inches to a motor is one of the easiest ways to add power. The second easiest way is to feed it. A cam helps do that. However, with that usually comes a price. Fuel mileage.
Cruise mileage wouldn't drop significantly, but there will be a decrease as you're using more fuel. The big drop occurs when performance mods are added to a machine, and the operator can't keep OUT of the throttle, enjoying the new found performance.
My RC51 got 130 miles to a 4.7 gallon tank, from the factory. After modifications, I got 90-95 out of a tank, and only 50-60 minutes of track riding before the "fuel" light came on.
The bike had a Power Commander in it, that allowed me to add or delete fuel from anywhere in the rpm ranges. With the assistance of a dyno, I could tell, via torque, HP and with an exhaust gas analyzer, where the MAP needed to be adjusted to get more power.
The ways to feed YOUR bike are a little simpler than my carbed Harley, but basically the same principle: Give it the proper amount of fuel through the entire rpm rev range in order to produce peak HP. Simply: Your bike can be MAPped through the computer. Altitutde, exhaust and air intake are all things that effect this MAP. Despite popular belief, open air filters or open exhaust doesn't benefit all bikes, or styles of riding.
The proper cam with the proper MAP would definitely increase your torque and horsepower ranges, giving you what you want, with a small decrease in your fuel mileage. For highway riding, you're in the midrange already, and that's where you'd have the cruising power that you want. The sacrafice *might* be a tad off your bottom end, that you may or may not even notice.
I'm not positive about this, but I'm willing to bet that if Harley Davidson offers a "Performance tune" for certain modifications, it's conservative at best, when compared to a performance tune applied by someone that doesn;t have to adhere to EPA reglations or the Federal Government in any way, shape or form.
Headwork: Headwork definitely has it's advantages for flowing better intake and exhaust, but it's not manditory for most street bikes. There are 95" engines putting out very close to the 100hp numbers with stock heads. Head work is proof that there's always room for improvement, and always ways to squeeze more horsepower out of an engine. If you were looking for 100+ HPs, then it's almost a must... No sense building a high performance engine and leaving the intake system stock, as that's like making an athlete breath through a heavy winter quilt....
Exhaust: Exhaust is just as important as any part you can add to an engine. An engine is an airpump, and the FASTER air gets in and out, the more horsepower it makes.
People have a misconception that BACKPRESSURE is what is the most important, when in fact, it's exhaust VELOCITY. All things given, backpressure directly effects this. Case in point:
How many times have you seen guy with 2" drag pipes, and no baffles? If you were actually gotten a base run on a dyno BEFORE the addition of the straight pipes, using the stock exhaust, you'd have seen slightly less topend horsepower numbers, but better low end and midrange numbers. Open exhaust reduces exhaust velocity, reducing midrange power and torque, with only gaining a few topend horses.
When I installed the 2" drag pipes on my bike, I took it out for a ride. It was loud and had the worst dead spot in the midrange, and dogged off the line. I installed Big City Thunder baffles, and upped my main jet to 180 from 165, and it felt a whole lot better. Still a tad lean in the midrange.
I finally ended up installing my factory head pipe with crossover pipe (equalizes exhaust pulses and crossovers are proven to assist in low end horsepower and torque) but uses Cycle Shack tapered mufflers and opened the baffles up a tad. I left jetting the same and the difference is noticable, with constant pulling from idle to 5200 rpms. It's almost as loud, but despite adding a little more weight, It performs better.
I've read that 2-1 systems seem to make good numbers on a dyno, when compared to the 2-2 systems Harely is traditionally known for.
Popping out of exhuast: I've found this can be cause by two common things: Reducing backpressure and an exhaust leak. Popping on deceleration is common as you decrease backpressure and with some systems, is hard to avoid. I know what you're saying, as I love a good exhaust note, but can do without annoying noises and popping that attracts attention or makes my ride sound like a POS.
Screaming Eagle slip-ons are hollow cans, with inserted, stamped steel baffles (air deflectors) inside. They're nothing special, nor overly researched, when compared to Vance & Hines or a few other brands. I agree.....it's hard to swallow $500 for new cans for just a tad bit more performance, bling or benefit.
Long winded, I know..........
Nathang, I'm not so sure, in your case, that adding cams would make you happy, but in reality, I think it will.
`Nother good article:
http://www.munising.com/harley_twin_cam.html
Although, I believe that it would deliver a noticable increase in your engine's performance without robbing you of too much fuel mileage. It's a personal choice. If you stayed with a cam (set) with a slight amount more duration and lift from stock, it would be enough to really wake the engine up with more fuel delivery and some much needed valve overlap. The last thing would be to apply the proper MAP for your engine, based on exhaust, CID, and intake modifications.
If you have the resources, and the extra money, don;t be afraid to have a dyno run or two performed to let you know exactly what you have now, and what if any benefit changes you make to your ride are doing. I say that "I notice a difference" when riding my bike after making modifications, but in reality, most people *think* a machine has more power when in fact, it's gained only noise. I refer to this as using the "Ass-Dyno 1000-i"
