Dual exhaust upgrade

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ranchodenieve

New member
I have been looking at the systems that are available commercially, but they all seem to have all kinds of bends in them. My stock system exits the 3rd cat and then runs straight back to the resonator and then straight back to a tee that splits it into the rear mufflers. No bends at all except at tee just behind the mufflers. A fat pipe feeds the tee and then skinny pipes feed the mufflers. I'm thinking that I could just put a crossover resonator in place of the 3rd cat and then run the pipes straight back to rear mufflers with the bends starting where the tee is now. It's a 1994. Is this a common setup or should I go with the multi bend system. I do eventually want to change the headers, but now I'm going for easy and quick. What size pipes are the best to use with stock headers, but give the ability to upgrade the headers in the future?
Also any ideas on good free flow mufflers. I want good flow and tone, but not loud.
Bill
 
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beerdog

New member
Well, exhaust options have been discussed a bazillion times but there is no harm in another thread. The common upgrade is to install a 2.5" mandrel bent system. There is an online exhaust company that sells cat-back pipe kits. If you want an aggressive sound install an x-pipe. Then pick some mufflers and tips. Just about any exhaust shop will be able to install it.

As far as headers, what you have are the stock exhaust manifolds. The passenger side has the CAT integrated into the manifold so removing it will be a bit of custom work, but it has been done.

Your next option is try cobra exhaust manifolds which are very cheap. The one draw back is you must remove and disable the EGR and secondary air system. I went this route, but would just buy Kooks next time. It is a bit of a hassle. Especially if you have to get emissions testing.

The next option is to upgrade to kooks headers with 2.5" system. This is your only off the shelf header option.

Finally, you could have someone fabricate a set of long tube headers using mustang headers to start.
 
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ranchodenieve

New member
I was thinking of using the crossover resonator to give the emissions people something to look at where they expect a cat to be. I might make and tack a heat shield on it to look good too. But, I've never seen any pipes that run straight back on any exhaust post. They all look like snakes with curves everywhere. Mine are straight now. Since the kooks are 2.5 inches, I'll probably go with that size and get kooks later. I am probably going to need cats somewhere when I get the kooks although they just run dyno here and only look under the car where the third cat is with a mirror. The standards are pretty loose here and stock it's way under the requirements. I might be able to delete the cats entirely if it looks good. But if I need cats, I'll need the big ones just after the headers. Has any one had experience with no cats under dyno emission testing?
 
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beerdog

New member
What state are you in? If they put a probe in your pipe then you will need the 2 forward cats. I do not think replacing the 3rd cat will make a difference. For the headers, many people use those spun high flow cats.

In Illinois all OBD2 cars are only checked for codes. Many of the testing facilities are OBD2 scan only. They look for if you have certain codes and if your monitors are in ready state.

Adding a cross over resonator will make your exhaust very quiet unless you have headers.
 
driller

driller

El Presidente
ranchodenieve said:
I was thinking of using the crossover resonator to give the emissions people something to look at where they expect a cat to be.
...
Has any one had experience with no cats under dyno emission testing?
Click to expand...
We have no emissions testing here but once during a state inspection, I was asked "About those cats..."?

"What cats?", I replied.

"Precisely the question!"

After which they proceeded to read me the riot act and inform me they were required by federal law and they could install some aftermarket catalytic converters on my exhaust. I said something to the effect I hadn't seen any federal marshals around town and I'll take my business elsewhere. Of course they didn't care.

I've heard of well maintained Mark VIII's pass emissions sniffer tests without any issues whatsoever, so it's possible if you pass a visual inspection, you may be fine. Then again, maybe not depending upon the inspector.

ranchodenieve said:
But, I've never seen any pipes that run straight back on any exhaust post. They all look like snakes with curves everywhere. Mine are straight now. Since the kooks are 2.5 inches, I'll probably go with that size and get kooks later.
Click to expand...
Straight? How do they route past the fuel tank and around the differential?

Image0023.jpg
 
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beerdog

New member
Rancho, post up some pics of your exhaust.

Many members have custom exhaust. There is probably nothing that has not been tried.

custom passenger side exhaust manifold mod to remove stock cats
custom long tubes (multiple examples)
kooks headers (many people)
famously botched long tube project (once)
custom mandrel bent
non-mandrel bent
cobra manifolds
X-pipe, straight pipes, resonators, blah, blah, blah

We have done it all.
 
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ranchodenieve

New member
I'm in Arizona. Since it's a 94 with no OBDII, they put sniffers in the pipes and I have to run it at 45 on the rollers. They put a mirror under the car to look for cats. This why I'm thinking crossover resonator in place of the 3rd cat. However there is no way that they could have seen the primary cats by the engine this way. They do open the hood and look in.
I looked at it a little better and it does curve out and under the gas tank just past the resonator. I think that I was just looking at the front and then the very back where the system splits. The hollow in the tank almost looks too small for two pipes. I see now with these pictures how to fit it in.
Bill
 
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