2006 F150 5.4 4x4 - Want to run duals with an X to take advantage of the scavenging affects of the X - Primarily a DD with a 6k lb TT to tow 6or7x a year. Plan on an intake with a tune - probably Troyer/VMP etc.

What do you think as far as piping and muffler design? I was thinking DI/DO Magnaflow 2.25" with a side exit in front of the RR tire. A shop suggested FlowMaster Delta Flow 40series 2.5" - They said I'll keep the bottom end because it's not a straight through muffler like the Magnaflow. What do you guys think? I'm in it for good midrange without the loss of bottom, headers will come in about a year (next tax return )

 

It seems that just about anyone who has run Flowmasters has said they lost low end torque. And just about everyone running Maggies say they didn't lose the low end. My advice, don't go with a di/do. Take it to a shop, have them cut off the y-pipe, replace with the Maggie X-pipe, and run 2.25 back to 2 Maggie 4x9 rounds. Keep it true dual, but don't run 2.5, that's too open, not enough backpressure. Openclasspro did it with his, I chatted in another forum with him about it. I believe he did that to the Vangina! He seemed really pleased, and I am about to do it to my truck like that.

 

Thanks...

Why not run the DI/DO? It would be cheaper and easier to install, no?

 

I have pics in my gallery. I have 2 1/4 with a x-pipe and two 18" magnaflows.

 

pics in mine as well

 

^^^ Just had true duels installed last week. 2 Maggie 14" mufflers with an x-pipe, 2 & 1/4" pipe. pretty much the exact same set up as Kevin24. Check out his gallery. I LOVE IT, LOVE IT, LOVE IT. Just haven't had time to post pics of my own yet.

 

Well I have 2.5" true duals, no mufflers, and a x-pipe, sideswept. I love the sound and the torque is still there bottom end, keep all four of my cats so that helped it, but def. my favorite exhaust to date, clips are below.

 

Just had my Dual exhaust done today, 2.5" with mag X pipe. Im supercharged though, sounds awesome with no mufflers!

 

I am getting ready to do the same. I have the mufflers and the X just waiting on time to get it installed. Anyone have a sound clip of this setup?

 

definetely 2.5" on a sc -especially 5.4 i recommend on a n/a engine to go 2.25"-especailly on a 4.6,i went 2.25 on my 5.4 and i picked up tq everywhere-my torque is very flat- over 300 ftlbs at 2k rpms and stays over 300 till 4300 where it starts to drop obviously

 

So I have a chance to grab some stainless Flowmaster DeltaFlow 2.5" mufflers that are not being used super cheap, I'm probably going to run 2.25" piping in case I don't like them and want to run magnaflows... we'll see how it runs

 

yeah-they can just flare the 2.25" to mate up to the 2.5" flows-a form of the static regain method by imploding the duct

 

Static regain method??? Imploding the duct???

Yeah..safe to say that's wayyy out of my league...lol

And again, with the FM not being a straight though muffler, I think it'll work. Uh...so, what's that static regain method anyways?

 

Please tell me you guys don't think that backpressure creates torque.....
The more open your exhaust is, the higher your motor spins and the more HP you make. The smaller the exhaust is, all you do is bring the torque down in the rpms more. However, you also reduce your torque as well. If you're all opened up with 2.5's and make 300tq at 4000 rpm, then put on 2.25's, you'll make something in the range of 285 at 3200 (approximations) due to the fact that the exhaust pulses move more quickly out of the pipes. Too small, however, and all they will do is keep decreasing power. The key is to find the optimum efficiency range for your motor and exhaust pipe size, which all depends on the amount of horsepower and how efficient your motor is.


I recommend 2.5's if you're using mufflers, especially if you don't usually tow. Towing requires the torque to be down lower, but you suffer some of the overall power.

I think i'll go write up an article that proves the exhaust theories and backpressure etc. etc. etc. and post it up by next week... stay tuned.

LC

 

He wants to run true dual. You make your 300 with single 2.5, if you go true dual and run 2.5, it's too open for n/a, but decent on a s/c motor. No, increased backpressure does not increase torque, increased air and fuel delivery increase torque, this is directly related to the cfm's of exhaust dumping out the rear, the more leaving means more has to be fed in, however there is a point where it is too open and effectively all you will be doing is burning more fuel and losing power. When your exhaust becomes too wide open, you will in turn be feeding in more air which can cause the engine to run lean and in turn burn your valves if you run it that way for too long. There are tolerances on our trucks, the pcm can adapt to compensate the a/f ratio only so much, and if you go doing things like adding an intake, and an exhaust with pipe diameter that is too large, you can run dangerously lean, the computer cannot adjust that much without a reprogram or using something like the xcal2 or 3, edge, or similar equipment. Do people run 2.5 dual on n/a 5.4 motors? Of course, and I'm sure they are happy as well, but for the optimum increases it seems that the several folks who have gone 2.25 have seen better gains all across the board. I will be waiting for your write up, i'm very interested in reading it.