Getting these to breath is fairly simple. In my case, I planned to swap in an FCR pumper carb, and add a different silencer. But the first step is to correct the unbelievably lame OE Honda exhaust flanges. For some (pathetic) reason, Honda welds up the pipe to the flanges unbelievably sloppy, so that the pipe is literally restricted 20% or more of its diameter. They do not bother to grind it, just bolt 'er on. Take a look:
That is not carbon buildup, it is the weld. Now, anyone who has ever tried to extract power from a motor knows that job #1 is intake and exhaust flow. Breathe, breathe, breathe. In this case, WTF?
A good chunk of time with the Dremel and you can begin to see the difference on the left side of the flange. This is still not finished, but it was so frickin' tedious I slipped into a coma and forgot to take another photo:
For the silencer, the stock one is not that heavy and worth keeping. There are inserts available on EBay that make it flow well, for very little $$$. But I wanted the looks factor of an FMF Q4:
Workmanship is great, but one step below the Pro Circuit pipe I have on my 650L. Sound is quieter though, the bike sounds good and is not loud. However, those loop clamps like in the photo are lame, hack, Rube, weak, etc.