I am looking for dual exhaust. I think I am looking for dual mufflers but don't want to get tied up with Dual CATS at least I think I dont. A few questions to get started and help my logic.

DUAL EXHAUST

1. Would adding a dual CAT affect my emissions? I now live in a state with emissions inspections every year.

2. Are there dual muffler and exhaust kits that start behind the Catalytic Converter?

3. Along the same lines of question #2 are there dual kits that DO NOT involve removing the spare tire?

4. Will doing any of this cause me to fail emissions inspection? I am in PA but I am sure most states inspections are pretty much the same except for maybe CA or NY.


I know flowmaster and magnaflow are the usual subjects but most of what I read involves removing the tire and I am not willing to do that.


CAI KITS

I figure K&N will be the most popular answer on this one which I do not object to just trying to save up. As a reference to that question there is one model that I am interested in, but it has two types. The first one has a aluminum tube running from the throttle body to the filter, the other type has a plastic tube. Any advantage of one over the other?

Also I noticed two types of tubes one with a single filter and another with two filters, again any advantage of one over the other?


Here are my objectives.

1. More HP.
2. Better Performance
3 Better fuel mileage (Every little bit helps on this one, I am not expecting a huge
increase but again a mpg here and mpg there adds up.)

I know more sound will go along with this, I am o.k. with this within reason. By that I mean more noise is o.k if it is effective I am trying to complete this and I do not want the noise to be obnoxious I figure the further back the muffler or exhaust the better. I know the K&N will make more intake noise and like I said I am o.k. with the noise for acceleration but I do not want a overly noticable increase in noise for cruise. Any suggestions?



MAGIC84

 

1. Dual CATs will not effect emissions. Installing 2 CATs you have to install 2 O2 sensors so all together they will just cost you a lot of extra money and do nothing for performance unless you have a Super Charger and mount headers and 3" cat and back duals. This is not needed unless you are going to do this so I think you're wasting money!

2. There are mufflers that start at the CAT and have dual outputs so you can go from single in to dual out after the muffler. Power performance gains come from this application if you go to flowing performance muffler like a Magnaflow, but there is no differance between dual or single out preformance 3" mufflers.

3. There are kits or just go to a shop that go around the spare. Removal of the spare is not needed. However there is no cut out on the drivers side for the exhaust tip so you people cut the bumper out a small bit to look like the passenger side of the bumper. You are better off going to a muffler shop and having a system installed.

4. Emissions and Inspection will not default for this upgrade.

I went for a single cat back exhaust (Magnaflow) with the 24" (I think) muffler that is SS that comes with a lifetime warranty. I had a muffler shop install it. (Mr. Muffler) Now I'm running all of my upgrades and with a 5.9L and I don't need any more exhaust flow. You want some back pressure. If you don't have any back pressure then you will burn valves.

My suggestion for you is this:

Go to a muffler shop and leave the original exhaust system to the output of the CAT. The OEM is Cat does a great job and is pretty good free flower. From the output of the CAT go to 3" piping. If you want the look of dual then install a Magnaflow single in dual out and pay for a complete new pipe that goes to the drivers side as well as the passenger side. This will give you no power only the LOOK. If you don't care about the look then just install a strait through Magnaflow SS 24" muffler (or it's 22") and 3" exhaust pipe to the rear of the truck as a normal setup.

If you want to upgrade to a more free flow CAT install a 3" Magnaflow CAT and a 3" Magnaflow "Y" pipe. Don't forget that "Y" pipe!

Either way step up to 3" from the CAT back. Install a drop in K&N and a ram air CIA that’s easy to do (look into the DIY write up on the 1st generation Durango main page) and I bet you will get about 2 MPG and a ton of power.

Here is a link to the custom Ram Air:
https://dodgeforum.com/m_966240/tm.htm

 

Unless you want to route the exhaust next to the normal passenger side exhaust dual exhaust from the headers back would be a PITA. There's a 25 gallon fuel cell in your way on the drivers side. Before committing to anything get under there and find a decent place to route that sucker and if it's feasible get a muffler shop to do all the work around your spare so it can stay where it is. I would go dual after the cat since, as hydra said, you're sticking with NA.

 

I don't know if it is still available, but GSM motorsports makes a custom Dual exhaust setup with dual cats and crossover for 1st generation Durangos.

Otherwise, I agree with Hydra's recommendation. Also, the 3 inch y-pipe, I think if you replace the exhaust plumbing from the exhaust manifold to the cat, it will make a big difference. The piping from exhaust manifold to CAT is part of the big restriction in the Durango's OEM exhaust system. I think the piping is like 2.25 inches. Pretty small. You can problaby have a custom 3 inch Y pipe built to replace that and you will have way better flow.

I wonder if they make a custom high flow cat that has 3 inch dual inlets and 3 inch single outlet?

For CAI, if you want to keep that OEM look under the hood, you can buy the slightly more expensive Mopar CAI kit. It is really nothing more than a rebadged K&N CAI kit. Keep the Mopar name under the hood!

 

Magnaflow makes a 2 1/4" dual intake to 3" "Y" pipe to solve this problem. There is no reason to go custom.

Really only one CAT is needed unless a Supercharger and headers are installed. There is no reason to pay for it unless your doing it.