so i picked up a 2004 wr 450 two weeks ago and i was going over the bike and i saw in the end on the exhaust it looked like a aftermarket insert so i took it out to see what it is and im not sure if it is stock or aftermarket so i took some pics and i was hopeing you guys could help me. i tryed to looked it up on diffrent sites and i cant find out what it is. the brand is gytr which i know is yamaha's performance parts that they make. The bike is very quite with the insert in and with it out is kinda loud if that helps. the last picture is the inside of the pipe without the insert can i ride the bike without this insert in? thanks in advance cameron. pics.