Looking to replace the stock muffler on my '99 F250 5.4 with something a little deeper and louder. I am going the cheap method right now, just replacing the muffler and adding a stainless tip. Any good sounding mufflers out there that will be a direct fit, or am I in for having to add a pipe extension because the new muffler will likely be shorter than stock? Thanks

 

I like the sound of the Hooker Aerochambers myself. I doupt there is a direct fit, but Im sure it would be easy to adapt it.

 

An FM70 BB2 or FM50 BB muffler with 3" Dual Offset In/Out will be the closest to a direct fit as the length is similar to the stock unit. You may need a short section of pipe however it will be minimal. The 50 series will be slightly louder than the 70 series. The factory exhaust is good from factory with the exception of the restrictive stock muffler.

I have pics of my F-250SD in my gallery.

 

Thanks guys for the replies. DKF, what exactly do you mean when you say "dual offset?" I know it has to have an offset if keeping the original piping, but with "dual" is there actually two inlets AND two outlets? Also I have researched the forums for brands of mufflers, and SOME people are saying that the Flowmasters actually hurt performance. I realize each has his own opinion, but is it really true that a simple aftermarket muffler replacement would actually provide LESS overall performance than the factory tin can? Dont get me wrong, I am willing to try the Flowmaster as much as anything else, but have you heard any proof that these mufflers can harm performance, or is anything aftermarket going to be better than the stock muffler?

 

Well, a straight through that does not restrict in diameter would certainly be better than stock, but a lot louder. I cut open my F150 factroy muffler and found it was 33% restrictive with one pipe at only 1.75" ID, while my piping is 2.25" (2.125" ID). The Aerostar's OEM-type replacement muffler was about 50% restrictive with not even a third pipe inside, but just a metal plate with 12 holes drilled in it.

When you replace the muffler, drill a couple holes in the end (one for flashlight, one for eye) and you'll see. Can measure diameter with coat hanger wire. Bend the end, snake it in, then see if it fits in the tube, if not rebend until it does, then measure. Close enough to tell.

Most stock mufflers are turbo style, that is three tubes, one in, one out, and one within, like a big flat S. After market turbo mufflers are better, like my Raptor, and not as loud as straight through mufflers. For the ultimate low restriction, just put a straight pipe instead of the muffler. Improvement is somewhat limited by the cats, but seems the factory muffler is the worst cork in many cases.

 

A dual offset muffler has both the inlet and outlet offset to one side of the muffler from the center line.

Heres a link:
http://store.summitracing.com/partde...5&autoview=sku

I have a pic of the FM70 that fits the SD with 5.4l and 6.8l in my gallery.

Flowmasters don't flow as well as some other mufflers on the market, however they still flow much better than the stock muffler and even the cat. The stock muffler is super restrictive especially on the SDs to keep the sound down because it seems many people who own trucks want them to be quiet and smooth like cars. The FM 70 and FM50 BB mufflers have a high capacity and even my 6.8l will not outflow it. You can see the mods I have on my truck in my gallery and the flowmaster did not have a negative affect on performance even with the mods on my truck. I have never been a huge fan of Flowmaster and I think they are a little overpriced however for the large trucks their FM70BB2 and FM50BB mufflers work great and I'm happy with mine.

 

Nothin more fun on a day off than watching your truck get new goodies on it at a shop! Had a 14" Magnaflow stainless Performance Turbo installed to replace the big 'ol muffler on it today, as well as a stainless tip welded on. All for under a couple hundred bucks. Is it just me or do our minds play tricks on us when we do something that MAY increase performance, even if just a little? Well, I dont know if it's my mind playing tricks, but so far I can tell a difference (however small) in responsiveness (torque). And I am sure it has noticeably more accelleration. Like I said, I am not going to lay down 100 feet of rubber anytime soon, but a definate difference has been made. And the sound is about perfect to me. A sweet, low rumble upon startup, mellows out at idle (but still a nice burble over stock), and noticeably louder, almost hot rod, on heavy accelleration. But the best part is that at highway cruising, its not much louder than stock. At cruising speeds that is a good thing IMO, as I used to have a Dynomax cat-back system that drove me absolutely nuts with droning at a particular highway speed I frequented alot (about 70)! Anyway very happy with just the muffler replacement, and with a 3" pipe from the factory I dont see a need to spend extra $ on a total system unless you want duals. My 2 cents.