I know this dosent happen to quads often but on my two stroke bikes the expansion chamber sticks out like a sore thumb just waitin for the next tree or stump to ruin my day. the way I do it is I take the pipe off and CLEAN the inside pefectly!!!!!. had one pipe blow out the plugs on me once, never again. I use a rubber freeze plug to seal the big end the I have an assortment of radiator hoses necked down to a valve stem. I put about 10 to 20 pounds of air in the pipe and use a propane torch to heat up the dented spots, use a propane torch it goes nice and slow and the heated air in the pipe will increase the preasure inside along with the metal being soft to round out most of the dents.
Mark
01 Honda CR125R
01 Yamaha Blaster
84 Yamaha YZ 80
69 Honda 450
63 Honda S 90
Mark
01 Honda CR125R
01 Yamaha Blaster
84 Yamaha YZ 80
69 Honda 450
63 Honda S 90