Originally Posted by Cranberry

I am in agreeable state with you sir! The cross member must be bent up a bit and needs to be bent down OR the exhaust is pushed to far down and under low load or downshifting is causing the Y pipe to vibrate more then usually hitting the cross member. When I switched to downpipes this same issue happened with me, had to press the cross brace down a bit to give more clearance, otherwise overtime I accelerated or downshifted it rattled bad.

Hope this helps!