I have a 2003 F-150 with a 5.4 and i was wondering what it would sound like and do to my gas milage to cut the muffler off right before the muffler? Also would a Y pipe with no muffler be the way to go? Any suggestions?

 

That would be pretty loud.Why not replace the stock muffler w/ performance one and leave the exit in stock location or just install w/o finishing the pipe.This will be cheap and it will give a good sound.

 

Would this be something i could do myself? What would it involve?

 

it'd involve welding or clamps. i'd say its relatively simple. just cut off the muffler and old piping and throw on a dump tip or weld on a new muffler

 

What kind of muffler would you suggest and how loud would it be?

 

You might want to consider a glasspack,

http://www.thrushexhaust.com/specs_glass.shtml

They sound good on a F150.