Headers vs Hi-op manifolds

This is an article on a 300hp engine. Headers would help even more in the 400+ range.
Mine puts out well over 400 and I am very happy with the results from TTI 1 5/8"-1 3/4" step headers as are several other Stock-classed cars.

http://www.moparmusclemagazine.com/...pp_0307_mopar_crate_engine_exhaust/index.html