Time for new exhaust - what to get?

[kythri]

So, I've been dealing with rattling cats for a while, and it's time to replace them.

I'm not opposed to a complete exhaust overhaul, but had some queries.

I've got a '99 XLT with the 4.0L SOHC. When I lifted it, I had Yukon 4.56's installed, so between that, the lift and the bigger tires, I've lost a fair amount of mileage.

As such, anything I do, it'd be nice to pick up a couple MPG if at all possible.

At the same time, I'd like a bit throatier exhaust sound - I don't want a loud, obnoxious poser sound, but something that just sounds "good", if that makes any sense?

I'm not looking to end up with a dual exhaust, but I'm not opposed to it if that's "better" - right now, it appears that the manifolds have individual cats on them, that end up Y'ing into the muffler, and out the single exhaust on the passenger side (that is, if I'm remembering correctly).

Is there any kind of consensus on 4.0L SOHC exhaust replacements? Would installing headers be good or bad for this engine?

Depending on what needs done, I may end up having an exhaust shop do the work for me, but after the new exhaust is installed, am I going to need to flash the computer to take advantage of any upgrades?

 

[FIND]

Well... unfortunately nothing you can do when it comes to bolting on exhaust will give you much additional mileage or power... BUT, headers and a catback don't sound half bad on an SOHC.

There is no real consensus on what sounds best or is best, but.... I think the best bet would be to look through other people's threads and registries to get their opinions on their mods.

 

[kythri]

Will ANY exhaust mods provide any increase, or all the advertisement just hype?

 

[2TimingTom]

In my opinion, it's mostly hype. While the engine is nothing more than an air pump and making the inlet and outlet paths more efficient should result in better power and efficiency, the computerized nature of it always keeps the A/F ratio pretty much stoichiometric unless hard on the throttle.

Old school muscle cars, not so much though.

 

[slickemhoundd]

not with explorers but with my mark viii's and s/c ive notices all around improvment from a proper double x pipe. mileage, torque and hp. All from the good ol dyno.

 

[sport97]

I have read that the after market headers don't make a huge improvement for the price. I would recommend a dynomax super turbo. Its louder but not loud (if that makes sense) Basically you can tell its not stock. I think everyone on here with one recommends it. Maybe run that with 2.5" back. Maybe throw high flow cats on?

That muffler is single in only so you could have a shop do the work, throw in 2 high flow cats, put a Y pipe in to a 2.5" pipe into the muffler and run a new 2.5" tail pipe out.

Regardless of the muffler choice a single 2.5" inch pipe seems to many to be the best route to go. Duals seems to lead to a loss of low end power.

 

[derek_redneck91]

Check out this huge thread for any ideas that could spark your imagination.
http://www.explorerforum.com/forums/showthread.php?t=192528 There's tons of videos online as well. Too bad the videos on youtube for my explorer dont actually sound like the real thing. I have also put tips on the exhaust now so it sounds much different too. Stupid Iphone. They take such ****E videos. And goodness me my truck looks like a piece of crap. Good thing I did a bunch of body work! Anyways, here's the photobucket of what I did with my exhaust.
http://s1242.beta.photobucket.com/user/d_mann2/library/Custom%20exhaust

 

[OneofMany]

If you have a cat for each bank id just run duals from the cat back. If yours is like mine and runs together before the cat with it mounted next to the trans (hot trans!?) id have a shop run new 2.5in and move the cat further back. I think the headers are ok.

 

[Dono]

Cut the rattling cats out, slip a couple pipes over the existing pipes and Y them in to a 3" pipe. At the other end of the Y, install a single high flow cat, At the exit of the cat, go 2 1/2" pipe to a muffler (A slightly restrictive one is ok for factory motor, and route to the back of the truck.

I did this, using a high flow muffler and it was just too loud and dronny (Spelling, if dronny is a word). I then added a small cherry bomb inbetween the cat and muffler. The sound is pretty throaty between the cam and SC on my ohv, but not bad. I needed the extra flow. Thats why Im recommending a slightly restrictive muffler for you. It will be quieter, and still flow more than your motor will push.

Hope that helps. I have had no issues with cel's regarging the o2 sensors.

Also, you better make sure you comply with emissions laws in your state. The fine could be far more that its worth.

 

[Dono]

or...cut the rattling cats out, and have cheater pipes welded in (Depending on your laws, thats the cheepest).

 

[J_Train]

I agree with Dono

 

[FIND]

The cats do a hell of a lot for noise and drone. Just leave them in. If you want dual exhaust, just split them again after the Y pipe. You aren't gonna pick up any power taking them out or taking out where it goes to a single pipe.

 

[Dono]

The cats do a hell of a lot for noise and drone. Just leave them in. If you want dual exhaust, just split them again after the Y pipe. You aren't gonna pick up any power taking them out or taking out where it goes to a single pipe.

FIND's right. Cat's do a lot for noise control. Although, if your cat's rattling (Coming apart on the inside) you do want to do something about it.

 

[FIND]

Meh, I'm just saying. If it were me, I would replace bad cats with good ones instead of pipe. 2 universal high flow cats are not that expensive, and neither is an OEM style replacement pipe. I think with the OEM style replacements... I might cut off the flange where it goes 2 into 1 and replace it with an aftermarket X pipe or Y pipe from a performance aftermarket manufacturer, or make one. From what I can recall, the pipes come down in the center a significant amount more in the aftermarket ones and choke the exhaust down quite a bit.

 

[Sams01XplrSprt]

i had single in and dual out 40 series flowmasters on my sport but now i sold my sport

 

[J_Train]

Meh, I'm just saying. If it were me, I would replace bad cats with good ones instead of pipe. 2 universal high flow cats are not that expensive, and neither is an OEM style replacement pipe. I think with the OEM style replacements... I might cut off the flange where it goes 2 into 1 and replace it with an aftermarket X pipe or Y pipe from a performance aftermarket manufacturer, or make one. From what I can recall, the pipes come down in the center a significant amount more in the aftermarket ones and choke the exhaust down quite a bit.

I think i have to agree with this. I would put a good quality muffler on it.

 

[will4vols]

Ive got Flowmasters with turn downs on mine, they sound pretty good, i recommend them

 

[jay 2000]

I put 27in. thrush cherrys on my 2 door. Ran both pipes out the right side behind the tire. Tight fit but looks-sounds good to me.