I have a 2005 Pontiac Vibe AWD (call it the Pontoyota) with an annoying exhaust issue. I've replaced the flange gasket between the down pipe leading to the second cat three times, the hardware, and even the downpipe itself but exhaust still jets out from the flange. Exhaust still comes out the tailpipe and there have been no indicators of backpressure from a clogged cat. The car is very loud until warming up and, while idling, I have to set the air to interior circulation otherwise exhaust gets pulled into the cabin. Can I just cut both ends of the flange off and connect with a 4" clamp? Is that flange there just for flex or does it have a more of an engineering purpose?