Hi I'm the second owner of a 2003 Fatboy FI is has been modified to a 1550cc's (not sure if it's a stage I,II,III not sure how to tell?) it has Andrews Cams, all gears no timing chain, Power Commander, Big Sucker intake/filter and a 2-1 V&H Pro-series header, it was dyno'ed tuned with all the above modifications stated to 92.5HP and 100.9Ft/Lbs torque</SPAN> (I have the paper work to back it up).
I want to remove and replace the 2-1 Vance & Hines Pro-series header and replace it with Vance & Hines Bigshot Staggered Exhaust PN17933 (has power chamber hidden crossover</SPAN>and standard louvered-core baffles), as I really want to get back to the old school Harley exhaust sound but louder that stock OEM pipes (I do like it loud) as the Pro-series header just isn't cutting it.

My questions are:
1.) What can I do by myself to adjust the tune after installing Bigshot Staggered Exhaust or nothing needed and is ok ride as is or will it hurt the engine?

2.) I'm thinking this will de-tune the bike some but how much power would I expect to loose on average switching to these pipes(?)

3.) I have very little knowledge of the Power Commander (is there various versions of the unit to be aware of) but willing to learn</SPAN> so what is involved to make changes, I'm computer savvy to a point, is this something for the novice or is this just something I have to take to a dyno shop and have done by them?

Any help would be appreciated.
Rick

 

IMO you are not going to hurt anything with just the pipe swap. You will loose some lower rpm power. It is very easy to make adjustments to the Power Commander, and companies like fuelmotousa and the Power Commander Dynojet folks have maps to get you started. The fact that it has been dyno tuned I would just leave it alone and maybe have it dyno tuned again with the new pipes if things aren't running as expected.

 

I agree as long as you don't get a pop on decel after changing the pipes. If you do you can save a copy of the dyno'd map and then start adding fuel to the lower RPM ranges to get rid of the pop. If it seems ok, the don't get it dyno'd. If you don't have a laptop, however, then you may need to take it back to be dyno'd. When I had mine dyno'd (at the time I had a PCIII) the tuner couldn't get rid of the decel pop which was due to the pipes that I have. I ended up getting a ThunderMax so that I could forget about dyno's every time I changed something on the bike. I have learned how to 'seat of the pant's dyno my bike with the TMax which isn't good enough for racing but certainly good enough for me.

C#

 

Your dyno guy should have been able to remove the decal pop with the Power Commander it is very doable. Basically it is just a puzzle to get a perfectly flat fuel/air ratio. I agree with you, it is not difficut the adjust the map on a Power Commander, but I found that if it's not running well after a intake or exhaust change, go to a good dyno guy and get er done right.

 

I went the other way -- from Big Shot Longs to a D&D Fatcat. Dyno after the change showed a gain of seven horsepower -- don't recall the torque gain but the ever-reliable butt dyno said it was definitely there, especially in the mid-range. So that is close to what you'd probably lose.

FuelMoto will only give you a new map if you can supply them the invoice number for your Power Commander. In any case their canned maps are hit or miss -- sometimes they work, more often they don't.

The only reliable way to make sure you're getting everything possible out of your bike is to get a good dyno tune.

 

Same as OldBoldPilot. Went from bss to 2n1 and had a sop increase. You will notice a decrease in tq low through mid. Sounds like you have a well runnin bike with $$$ put into it. You dont realize how good 100 lbs of tq is for a 88" to 95" bike. I'd leave it alone.

 

The pipes that I have aren't made for the street. They don't have enough low rpm backpressure. He was trying to follow my request which was as much power and mileage compromise as possible. It actually did fine until I moved down out of the mountains.