I need a new muffler for my F250 96 cc shortbox 4x4 7.3. The diameter looks to be 3.5", I assume that is stock size. Any recommendations on a good low restriction muffler or should it be updated to 4"? Would a new down pipe be needed with 4" update? What would be a rough cost estimate for a 4" upgrade? Thanks.

 

replace it with a peice of straight pipe

 

jump on Ebay....you can get a complete exhaust from the turbo back for about 300.

 

Yes you MUST change the stock down pipe, its very restrictive, go with one to 3 to 3.5 or 4".