I wouldn't lose any sleep over it. You said yourself it's not a race car. Whatever power that S might cost will never be felt by you in the real world, assuming there is any cost.. Just look at Dave Dudek's F.A.S.T. Roadrunner. Runs 9's through manifolds and a stock appearing exhaust system. I think the biggest restrictions on exhaust flow is mufflers and tailpipes. Kevin
Hey there feets, I saw your question so figured i'd chime in. My motor and car are a bit different than yours ( I have a 72 Fury Wagon, 360 automatic transmission ) but I did manage to fit a pair of Sanderson block hugger headers on mine.I just had to replace the original starter with one from a early 90's Dakota. I put some Flowmaster 40's and duals all the away back and all seems to work well.