if i swap out the stock headers on a '99 4.6....will I have to change the exhaust to get the full effect...any help would be appreciated...I have always wanted a truck and now that I have one I need to tweak it a bit to maximize my gas consumption as much as possible...100 miles round trip to and from work =)

 

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Thanks max.....but I think ill just swap out the whole system from the converter back.....certainly like the sound of those flowmasters. =)...i appreciate the time you took to answer and im sure i will continue to annoy you guys for a long time to come with lame questions...and odd viewpoints .

Randal9