there is actually no gap. it does look that way in the pic due to shadowing from the flash, but if you blow it up, you'll see it's flush. i poked a file around where the flanges meet. definitely gonna put in a gasket soon, this was an impromptu look/adjustment and during after store hours. as far as i could tell its sealed up on the backside too. it just never hit me that the slotted holes on the downpipe meant it could be adjusted, im retarded.
my cabin used to reek a bit of exhaust (kinda used to it from the older cars Ive had), it's nonexistent now. I take a deep whiff at stops and slightly confused i don't smell anything haha.