I didn't have to switch headers(Hooker two inch fenderwells) on my Duster when I went from MCH CNC ported Eddy to a set of the SR that where M.W. port size when I bought them. The M.W. SR with the proper Indy manifold was quite a bit faster (.2+ a little on the ET)than the Eddy where, the Eddys flowed 310 at 28 inches and the SR flowed 340 CFM at 28 inches on the same bench If you decide to buy a set of the SR buy them with the M.W. ports and change the intake to match