I decided to go ahead and have a second upstream bung added on bank 1 of the headers for my wideband sensor so my AFR readings will be more accurate. Got that welded in today and I tested the exhaust manifold bolts that aren't broken to see if any more would break as I'm trying to remove them and surprisingly they all broke loose. I have 3 broken ones- 2 rear and one front. I have the Dorman clamps on hand to take care of that problem though so I won't need to extract the broken studs in the rear at least since there's no room unless I was to use the welding technique, since I don't weld. The front one I'll try to drill and use an extractor and if I fail I have the clamp. I crawled around under the truck today and measured for the headers and it looks like they'll clear the crossmember but it will be close. These don't have a Y-pipe, they have 2 separate 3" pipes that connect at the stock piece where they go into my double in, single out muffler. Just like the stock Denali system. So my plan is to install the headers tomorrow. I'm a bit nervous but after checking the exhaust bolts I feel better. I just don't want to get into a situation where the heads have to come off obviously, especially with the blower. As far as the downstream O2 sensors, I have 2 new ones ready to install if Blackbear ever gets back to me to say if they'll work ok.
View attachment 86678
View attachment 86679
View attachment 86680