Dual Exhaust

[Concept156]

In May, it looks like I am going to do a major overhaul on my truck. (as long as cash is flowing then) I've got a 95 Limited and some plans. I was going to start with a 4" Trailmaster lift and some 33's and then a paint job... I am not quite sure what color yet. But, since I will be working out this stuff already, I was thinking about dualing out my exhaust. I was wondering if there is any way for me to know whether or not my Explorer will pass emissions afterwards... My plan for the exhaust is to get a set of JBA headers, followed by a couple of freeflow cats from Summit Racing, and a couple of Gibson mufflers, and to link it all with 2.5" pipes... It will look cool and give me a little more power (especially in the mountains), but I still need to be able to pass Colorado emissions... could I just assume that it will pass because I have two cats each with half the volume of exhaust running through them?

 

[Alec]

You should pass emissions testing. You're truck is over 4 years old, so I think it's legal to mess with the cats. I don't think it's a question of passing emissions, but passing inspection. Some inspectors give you hell if you put an exhaust tip on, let alone redoing the entire system. I haven't had a problem with my truck yet, but I haven't messed with the cats. In fact, the inspectors are always impressed with the very low emissions of my truck.

Just wondering, are you planning on just running two parallel systems out the headers? Are you going to X or H-pipe the system? Your emissions will be lower if you dump into two series cats, then into a single in/dual out muffler, rather than with 2 parallel cats and mufflers. Actually, you really should do it that way to keep some backpressure in the system. Remember, if you free up the system too much, you'll lose low end grunt. I lost a little low end torque when I put the headers on, and that's with the stock cats and a 2.25 single out.

 

[Concept156]

Thanks... Just wondering, what does X or H the system mean? I really don't know much about cars... I am slowly learning, but I hope to learn a lot from my stepbrother who is the guy that is going to help me do all of the work I've got planned for this summer... Oh, and the inspectors... I am assuming they look at your system during emissions...?

 

[Alec]

Stock, the exhaust manifolds go to a Y-pipe, then through 2 cats in series, then into a single in/single out muffler:

My recommendation is that you get the JBA headers and bolt them up to your factory cats. The JBA's come with everything you need to mate exactly to the stock cats. If your cats are working fine, don't touch them. You could lose too much backpressure or mess with their polution control abilities. After the cats, change the muffler and the tailpipe. If you want dual exhaust, get a single in/dual out muffler. I only have a single out and the JBA's, and don't have a problem with exhaust restriction. In fact, I know I'm flowing well because when I put my headers on, I lost some low end grunt. Like I said b4, if you free the system up too much, you'll lose torque.

As for the inspectors, they're usually cool as long as you don't mess with the cats, then they start asking questions. In TX, there are laws restricting mods you can do to your vehicle if they mess with emissions.

Mustangs and other true dual exhaust vehicles run two parallel exhaust systems. These two systems should equalize their pressure to keep everything working well. Here's a Mustang X-pipe system:

Dead Link Removed

The headers connect at one end, and the mufflers (then tailpipes) at the other. That X equalizes the pressures and exhaust pulses. An Hpipe system is less efficient and obviously looks like an H, not an X.

This is fact mixed with my opinions. If some of my facts are wrong, sorry. I just don't like to see people spend $$$ and time only to be unsatisfied with the results.

 

[tac0meat]

true duels on a v6 is gonna be pretty hard to do. your much better off doing headers than combine them into a single pipe. having it combine into a single pipe usually helps increase torque on a semi stock engine more than true duels do anyways, because each burst of exhaust gas helps to draw out the burst behind it(boosting torque) you can get a good sounding free flowin cat back installed for around $200, well worth it in my opinion. a new exhaust system is probably gonna give you the most hp per $$$.

 

[Concept156]

Thanks a lot guys... I will probably just have swap out my muffler for a single in dual out then... that will be a lot cheaper and easier Hopefully I will get some pictures of it when I get it all done...