I agree that extrude honing would be a great way to go with these manifolds, but a few of the runners are too narrow to allow a larger I.D. I was originally going to fab some tubular stainless manifolds, but if I can meet my goals using the cast Jet-hot coated manifolds I already have, I believe they will be more durable. I need to fab some stainless 'up' pipes, do you guys think 2.5" from each manifold will be OK? I have pretty much decided on an S-85, it will have at least a 4" dp. Do you think I will see 1K from this set-up?

I won't get upset if I don't get there on the first try either. I can re-work the pipes at any time since I am fabbing them myself, I may even have a set of tubular manifolds available from a C5 Corvette twin kit. I already have a set of slip on 1 7/8" primary Edelbrock 4-1 merge collectors from a previous project, but I am unable to weld all the way around each primary so I though they would leak too much if I tried to use them. You guys just let me know which option sounds the best, I appreciate the advise.

 

Extrude honing and coating my 6.0L manifolds was more than the bassani headers I ran for a year and the SW headers Chuck@FLT made me buy (dadgum 4L80E!!) combined

 

I think 2.5" would be too small for that big turbo and a 408. I'd do 3" and coat inside and out.