I keep hearing conflicting stories on what is the best setup for " true duals". Smaller pipes for better torque..... Place H/X-pipe here.... Lager pipes are the way to go.... H for low end, X for high end.... SI/DO better than DI/DO.... you know the stories.

Would someone help a brother out?

I have a '98 F-150 4X4 S/C w/ 4.6L w/4R70W and a 3.55 LS running BFG MT 33's and 100+K on the motor. My only mod to date is a MAC cold air intake.

My future mods are to included a Superchip from Troyer, E-fans, underdrive pulleys, and a polished throttle body and ported/polished TB elbow. A gear change to 4.10's might also be in the works in the future.

So with that in mind can someone tell me which exhaust setup would be best for all those mods listed?

I was planning on doing a "modified true dual"(Y cut out) using Magnaflows DI/DO 11385 muffler w/2.25" piping EXITING IN FRONT OF THE REAR TIRES like the Lightning. I definitely want the pipes exiting like the Lightning.

 

Your idea is fine. Highly recommend the X-pipe, but Magnaflow has it built into their DIDO mufflers. Dual 2.25" would be better than 2.5". The best setup for F-150's is single 3" after the cats, IMHO.

 

APT,
Would you recommend me placing the DI/DO closer to the engine or a little ways back?

 

As close as possible in theory, but I don't think you'll notice the difference you have between cats and the rear axle.

 

Just an FYI, not all Magnaflow DI/DO mufflers have the built in X-pipe. The ones that have that feature usually have an asterisk (*) next to them in the catalogs. They are 14" 4x9 mufflers in both stainless and aluminized steel.

Lookeee-lookeee

 

Thanks for the FYI LE PEW. I already knew this.

 

I mounted my DI/DO Flowmaster muffler in the stock location to take advantage of the heat shields.

 

Beerman, which series DI/DO Flowmaster did you use and how long was the case??

Thanks.

 

My muffler is a Flowmaster 70 series "big block muffler" and the case is approximately 24 inches long. It provides a pleasant mellow tone, that you can hear going down the street, with no highway-speed drone.

 

I have the true duals with the dual in/out magnaflow and I HATE IT! not loud at all. But it did help out in the low end department.

 

I have true duels on a 97 f150 with the 4.6L. It was done at a custom exhaust place. They went with 2.5in pipe with 2 12 inch glasspacks, into 3.5in SS tips. Its pretty loud, though I lost a little torque, but gained power on the higher rpm. Its deffinately louder with true duels than a single pipe splitting into duel tips. I'm pretty happy with how mine sounds, hope this helps.

Josh

 

There's NO comparisson to true duals! I've heard the flowmaster single in/dual out 40 series. Its alright. I showed the same kid mine and then reved it, the kids mouth hit the floor when he heard how loud it was.

 

Question about true duals, I know it is like this on my 89 f-150, but the pipe coming off the header/manifold on the driver side has got to go around the gas tank. So at one point the pipe from the driver side header and the passenger side header are right next to each other, correct? Also, I dont have true duals, but am highly considering it, what do u suggest for a muffler? glasspacks? Flowmaster? Gibson? Magnaflow? 2 seperate mufflers? DI/DO? Thanks for your responses.

 

on mine they cut off right where they had originally welded the 2 sides into one and just ran 2 new pipes from there.

I went with flow 40's first then switched to a single magnaflow but will be going to flows again.

 

I have the Magnaflow stainless 5x8 oval tru-x muffler, part #14468. It has an 18" case, not the 22" case. The 22" case muffler might have been a little better for me, slightly more quiet, but the 14" case muffler would definitely been too loud for my tastes. I think I made the right choice. I used 2.5" pipes up to the muffler with 2.25" tails out the rear. I probably should have used 2.25" all the way, but it turned out fine for me. I have a 5.4 and I don't tow. Here's a link to my Magnaflow install gallery and a couple of photos:

http://ftw.truckmoxie.com/mygallery....27&album=32236