heres my problem. on my b20z i have a gsr stock exhaust header. it does not have an o2 sensor bung. theres is also a header to cat clearence issue that i need a exhaust shop to fab up when i get this swap done. would putting an o2 sensor bung into that extra extension ( which is before the cat ) be a good place to put the o2 sensor? i figure i can kill two birds with one stone with getting a bung welded in there while its at the shop.