ZZP downpipe with cat have room for O2 bung?
 

I tried searching, but "downpipe" triggers hits for everyone's signature. Does the ZZP downpipe for the shorty header with 400 cell cat have room between the cat and flex joint for an O2 bung to be welded in? Also, while on the subject of downpipes, everything I have read, I am good to go with 2.5 exhaust staying M62. Is there any benefit to running a 3" to 2.5" downpipe since my badmab header has a 3" exit? My gut says to just go 2.5 all the way but there is a ton of varying information across vehicles in general. I did research but without getting into the science of it I am lost. Thanks!

So related topics kinda answered this one, but I cant delete the post.

I would think there should be room because there is room on mine and I have the downpipe for long tube header.