This is a write I did a few years ago regarding modifying the standard stainless steel muffler which was stock on the 03/04 WR450F. The stock tailpipe on this muffler was very restrictive.
Once again, when funds are very tight and one can’t afford / justify the purchase of an aftermarket pipe, it is always a bit of fun to improvise. It is very satisfying when it all actually works and costs next to nothing to do. Once again, this may also be applicable to early WR250F’s.
Rather than redo the writeup here, here is a link to a site that originally hosted it. (mods, if this is a problem, PM me and I will try to redo it on this site.)
http://www.dirtbike.ws/node/4734
