my 2002 accord 4 cyl camewith a stock flexjoint right before the cat. My dc sports headers came with a flexjoint built in the downpipe placed right before the cat. When i got my car on the dyno we had the hood open of course and ran it to redline in 2,3, and 4 gear. I was watching the motor when he was running it, and the motor moves pretty drastically when changing gears and really getting in to it.