I didn't like the loudness of the FMF Q2 pipe my new DR came with, so I did a little research on the innertubes, and got a cheap pair of 1st generation Hayabusa pipes in fine shape. I considered trying to fabricate a 3-hole flange and midpipe, but didn't have several of the tools I'd need.
So, I got the left-side 'busa adapter kit from Jesse at Kientech.
Closeup of the flange
I removed the FMF, loosened everything up, from the header bolts on back, loctited the bolts, attached everything loosely, lined everything up, and then tightened it down into place.
Mid-pipe mounting point
All back together, with Dirtbagz rack
The 'Busa pipe is longer and probably a pound/pound and a half heavier than the FMF, but the fact that it never needs repacking, as well as the quieter (though still raw and fierce, esp at higher rpms) exhaust note made me decide to make the change. Now I just need to find a way to get a spark arrestor in there...
Next, it was time for a dyno run.
I'd already dyno'ed the bike with the FMF, and here was the result. The green line is the new 'Busa pipe; the red line is the old FMF.
When I ran my stock-exhaust, mildly-jetted old DR, it got a whopping 32 hp at the rear wheel.
With the FMF, it topped out at 35.15; the 'Busa pipe was ever so slightly less at the top end, with 34.82 hp. The surprise, for me, was the rather improved low-end torque with the 'Busa pipe. It's slightly less torquey than the FMF at 6-7k rpm, but has notably more oomph pulling away from lights, up hills, and is, ahem, easier to wheelie.
Bike has a stage 2 Dynojet kit with a stock 40 pilot jet, 150 DJ main jet, needle on 4th clip, Twinair filter, and Jesse's cut airbox. Header is stock.