As long as it's a competent exhaust shop doing the work, that way's just fine IMO
**oh, and just FYI....headers/full exhaust can be a MOTHER. I did cal speeds with full exhaust on my truck, never again. Just do research, research, research and just plan for twice the time to get it done right. Idk about the AWD system, but my cal speeds didn't fit for shit on my 4x4. It all comes down to what it's worth to you, me personally, unless it's a built motor or you're 2wd, I'd just stay with stock manifolds and do full exhaust