Welp, laying in the snow melt under my truck isn't much fun, but it's done. Noticed the Remflex 7010 has a hole between the two middle lower stud holes. Apparently this is a channel to the EGR passage (I think) as it was clear exhaust was coming out of this. The DT header has a hole there too, not sure why, but this was the cause of the leak.

So, one Napa gasket later and I'm quiet again

So, for those with a header that also need to run an EGR, there does not appear to be a Remflex gasket that will work for you. Lesson learned.

EDIT: Doing a little internet searching, I am seeing some header setups where a bolt is threaded into this center hole. Didn't think to check and see if this hole was threaded or not. Does anyone know if it comes stock threaded? Sort of a bummer if I could have just tossed a bolt in there.