Originally Posted by beemw
-For flaps to stay open on stock exhaust, you need to get a clamp or even heavy duty zip ties( but the plastic might melt) and you need to squeeze the flap open amd thrn clamp it against the arm of the butterfly vale, it sounds complicated, its easy actually.
550's exhaust is not like a 335 for example where you can pull the vaccum line and keep it open, it uses vaccuum to open to valve so by disconnecting it, your valve never opens
You need to use metal clamp on the top actuator thing to hold it open.
Im sure, that + downpipes will be the way to go.
Appreciate the reply man..I went ahead and had a custom catback made and Im pretty satisfied with it for now