I have a 2002 f150 supercrew 5.4 triton v8 and I'm going to cut off the factory muffler and put a dynomax bullet and I was wondering if I should run the exhaust pipe off the muffler or run a Y-pipe off the muffler and then have duals? If I have duals will it be louder?

 

If you want it louder you could just leave it without a tailpipe. It will be loudest with nothing attached to the muffler. I would think the y-pipe/duals vs single pipe is all going to depend on diameters and bends of piping chose. For example if you ran single lets say 3 1/2" with clean mandrel bends vs dual 2" with kinked bends the single will more than likely flow better and be louder but equal size and bends a dual should be slightly better/louder. I've never tested these sizes and do not claim to be an expert but I have had several custom exhaust all a little different but all on different vehicles so these are my perceptions not necessarily facts.

 

So just leave one end of the muffler without any exhaust pipes? Is that illegal?

 

Depends on local law I guess I should have mentioned that sorry in Texas as long as the exhaust exits 12 or 18" (can't remember which) behind the passenger compartment it is legal so it wouldn't be on a car or suv but is on a truck because of the bed. Find a reputable muffler shop and ask them or search the Internet for your local laws.

 

Sorry I should have added to check your local laws in Texas it has to exit either 12 or 18" behind the passenger compartment I can't remember which. So it's legal for a truck but not a car or suv.

 

I had a buddy with a 4.6, had an open muffler. It sounded pretty good, it wasn't obnoxiously loud, but it was louder even at an idle it was pretty damn hearable. It sounded good in my opinion, thinkin about doin it myself. At once he claimed to have cut open the muffler and weld a straight pipe in place of the core, but I doubt it. It sounded pretty good, and if it don't work out, it ain't like it's permanent. But the guy above definately sounds like he knows wut he's talkin about:P so I'd listen to him

 

So most likely if I get a muffler larger then 18" I should be fine

 

Colorado law says it has to be past rear axle so that carbon monoxide doesn't go into the cab. But my truck I think the muffler is under the bed so I think without the exhaust pipe I'm ok