LOL! I know what you mean. When we fired the Roadrunner up those foil ducts went totally spastic on us. I didn't expect them to jerk around so violently. It was like watching a Sasquatch have an epileptic seizure. One side blew off right away and the other tore just past the end of the exhaust pipe. I ended up using zip ties to hold the pair together and then placed a transmission blanket over them to keep them from jumping around. I'd seen that you modified your setup with solid tubing. - NOW I know why.