You can get a WR exuast they are spark arrested. Most pipe manufactures have a pipe that is adjustible for it to be a spark aresstor. AKA Pro-C T-4 system.FMF make's a pipe too. I belive other company's have system's but just can't remember what they are.
Well a little ingenuity saved me some big bucks! I didn't want to pay $130 for the BMP kit and don't need or want a new pipe yet. But, in order to ride in USFS areas, we have to have a spark arrestor right?!
Well I drilled out the 8 rivets that hold the end cap in place, cut a piece of 1/4" mesh screen to fit the hole (with four "tabs" sticking out to hold it in place), put the end cap back in, and 8 new rivets later I have a spark arrestor that will pass the "stick test"!
$3 for rivets, some leftover screen and about 30 minutes was all it took!