So, I have a question. I drive a 1999 f150, 4WD, 5.4, with all stock exhaust minus one replaced cat (universal), and brand new OEM exhaust manifolds on both sides. I want to put cat-back duels on my truck, and i dont want crazy loud or obnoxious tones or popping. The truck is just too damn quiet for me. So im looking into either Duel inlet/duel outlet magnaflows, or just two straight through magnaflows, with side pipes coming out behind the rear tires on both sides. Is there anything you suggest i do to keep my engine healthy and long lasting? its at 175,000 miles and the only problems its ever had is rust. do you have any suggestions on pipe diameter also? i was probably gunna go into the 2.5 to 3 inch range, but i dont want to mess up the factory tune with flow issues. thanks.

 

Unless you really must have duel out, straight through is just fine and a little louder.

A 3" cat back with the factory original Y set up is the best you can do AFA performance. Not sure it will be loud enough for yuh tho...you'll definitely here it.

The Dyno showed gains with the EXPY's bumping up to 3" for cat back only...no other exhaust mods and running the original tune. Sticking with 2.5" is fine as well...you not going to lose anything performance wise.

 

Sorry if this sounds stupid, but what does "EXPY's" mean? and id also prefer true duels...from the cats back lol...but im open to an X/H pipe if you think thats a good idea!

 

Expys= expeditions
True duals are just that... they are duals from the engine all the way to the exits. You will never have true duals from the cats back. You'd have cat back duals. I'd think if you did cat back duals you'd want to stay 2.5" but listen to jbrew, he's one of the resident exhaust experts for 10th gens.

 

Magnaflow is a good choice. They have some throaty muffler options that won't have you taking it back off in a couple of months because it's more annoying than cool. There are a lot of those options available.

 

Right, just ask anyone who comes around on Bratwurst night.

Thanks Fordguy. Yea, I think he is looking to do a single in and dual out. Uknow, transition through the muffler....SIDO.

Is that correct Krsenor ? That's fine, doesn't matter.

 

Well I had in mind cat-back duels, duel in/duel out. but I want to do whats healthiest for my truck, and if you guys believe keeping the factory y-style is what I need to do, that will weigh heavily on my decision, thanks guys!

 

I am no exhaust flow expert,but I would cut the y-pipe off...it has a terrible merge/size where it comes together.
On my 2000 5.4, both cats on the drivers side were melted and stopped up.So I gutted all four of the cats and it had a SIDO old flow-pro muffler and 3'' tips out at the bumper and it was very quiet.It may have been due to the hollowed cats but it was quiet.
I would cut the y-pipe and run two pipes and no muffler out behind the tires,I think the cats will keep it toned down but yet still loud.

 

There's always one that does things differently

Sigh.....

 

So ive decided that either way, i want two pipes coming out the sides behind the rear tires, and ill probably do a single inlet/duel outlet setup. 2.5” pipe. Im looking for just generic cheap angle cut 3” tips, anyone got any suggestions as to where i can find some?