APH all day long
Agreed on this. Keep in mind a muffler will have to be sourced from another guy on here.
You haven't stated what other mods you have done, if any. If you haven't done any other than perhaps throwing in a K&N, you'd be extremely disappointed with the results of what you asked for.
The engineering has already been done and by Buell no less. The various diameters and runner lengths were already carefully engineered by Buell to run the best throughout the rev range, whether it be stock headers or their race headers designed to work with their race ecm mapping.
Simply making larger diameter pipes all the same length (no graduated steps of a certain length) does 3 immediate things.
1. It will run leaner and pop like a muthafucka.
2. It will have lower volumetric efficiency because you ruined the ability to scavenge properly.
3. You will lose torque an HP everywhere and whatever you do have will only exist at the higher rpms.
Losing the muffler also exacerbates the problem giving you more of 1 through 3 and adding result number 4... sounding like a twat for no good reason.
The differing diameters and runner lengths are designed to facilitate the pressure waves coming from the combustion chamber to travel back and forth in the runners. The length is determined by requiring the negative pressure wave to travel back up the header and hitting the combustion chamber as soon as both intake and exhaust valves are open so it can scavenge for the best cylinder fill. The designer will select what rpm they want that to happen at. For a cruiser, lumping along, it is shorter for max torque at a low rpm. A race bike will be shorter for more torque at a high rpm. It's all about timing.
My land speed bikes were made to only run WFO at max rpm...up to 8000 rpm. It ran like shit everywhere else. I had 4 steps of differing lengths and no muffs so that all my power was between 7 and 8k. I was getting 270 RWHP on a DynoJet 250 eddy current dyno out of a normally aspirated 1650. The lower rpms were still high compared to a stocker but the ramp up was extremely steep and didn't kick in till 5k.
That's very good information and some way beyond the limits of my understanding, thank you for taking the time to reply.
I have noticed some power loss since removing the stock exhaust and fitting the Jardine (still on standard header's).
I am not searching for ultimate power or speed, if I was looking for that i'd be looking at a different manufacturer and different style of bike.
What I am after is a bike to use the way I like to use it, having had various riding phases over the years I now find I like to have something a bit left field, I have a Harley which has been with us for 10 years (has open short shots fitted) also have 3 70s zeds, so the role of the Uly is primarily early season and late season riding when the weather discourages me form riding the other bikes, as for sounding like a twat sorry but the noise the bike makes is part of the enjoyment of riding for me no more no less I just like the bike to sound good, and if I have to loose a bit of power then that's fine as long as I'm not harming the engine somehow through altering the flow of exhaust gasses, with my limited knowledge and from reading forum posts I had assumed that the ECU could be altered to account for the change of exhaust.
I've had BMW,2 Triumph and 2 Yamaha ADV type bikes, I don't think I need the ever increasing level of tech and sheer bulk which is now built in to these bikes, I find the lighter lower tech Uly suites me better having previously owned 2 other Uly's and regretted selling them I am for the moment satisfied with what the Uly offers and is.
please keep the advice/comments coming.