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post #1 of (permalink) Old 08-31-2006, 05:12 PM Thread Starter
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Exhaust Questions

Alright... getting serious about doing exhaust, so I started calling around (Austin Texas).

I call this one joint up, and he starts telling me that I can't get a true dual exhuast on my truck because of the placement of the cat. Says that after '82, the cat has to stay where it was from the factory. He suggests no headers, and a 3" pipe all the way back.

So here are my questions....

1) What exactly is the law regarding this?

2) Why can't both cats go on the driver's side where the original was? That's where I figure they would go anyway. No room on the passenger side because of the tcase.

3) How much torque would I lose by putting headers on?

4) How many of you guys are running a true dual system? Likes/dislikes? Where did you get it done, and how are your cats run?

This guy sounded very knowledgeable, but he didn't give me the answer I wanted to hear.

The other shops I called just gave me a price... no info on why they can or can't do what I want.

Anyway, thanks for the help. I'm hoping to get this all done in the next month or so....
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post #2 of (permalink) Old 08-31-2006, 10:14 PM
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Re: Exhaust Questions

In the shop here where I got my exhaust done, they had the state law concerning exhaust posted on the wall.
I got true duals on suburban. Long tube headers, two cats, and two mufflers. The guy tucked everything up inside the frame rails real nice.
The cats are on either side and just behind the transfer case. With it being a suburban, we had plenty of wheelbase to work with.
I removed all stock exhaust, put on the headers and then drove it to the shop. If I had gone to the shop with the factory exhaust intact, they would not have given me duals. They claim that they can only put on the same type as what the factory did. I guess they figure that if there is nothing, they can't prove what was on it before.
Anyways, would I do it again? Probably not. I don't like the long tube headers because they're too close to the front shackles. And with two of everything, there is just too much stuff under the truck.
Next time I'd go with short tube headers, or keep the factory manifolds and go with a single system, just bigger tubes.
Sorry for the long reply, but hopefully this helps you somewhat.
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post #3 of (permalink) Old 09-01-2006, 01:00 AM
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Re: Exhaust Questions

If it's a stock motor, I'd keep the manifolds. IMHO it's much easier to install manifolds with gaskets and not have to worry about the gaskets leaking or needing to change them on a regular basis. I've just heard lots of horror stories about leaking header gaskets.

I've got dual 2.5" pipe from the manifold back through a set of Flo-Pro mufflers, this is on my '83 GMC w/400sbc. If I had it to do over, I would use 2.25" tubing, and have an x-pipe in there. The 2.5" is just a hair to open, the exhaust pops irritatingly if I don't shift it (standard tranny) just right, especially when it's cold. I've got a heat riser on the passenger side between the manifold and the start of the pipe, beofre it opens you can really hear the difference in side to side, one of the main reasons I'd have an x-pipe installed next time.

If I ever decided to go single exhaust; then I'd probably come off the manifolds with 2.25" or 2.5" have them both enter one muffler, with a single 3" out.
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post #4 of (permalink) Old 09-01-2006, 06:30 AM
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Re: Exhaust Questions

I did have problems with leaking gaskets until I changed to the expensive copper gaskets. They cost quite a bit but very effective.
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post #5 of (permalink) Old 09-01-2006, 02:21 PM
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Re: Exhaust Questions

i have had no problems with long tube headers. but i'm using good gaskets and checked the bolts every 40 or so miles after i put the headers on the motor. you will likely get an extra turn out of the bolts as the gasket shrinks and things move around.

FYI-the heat will kill your starter with long tubes, unless you shield the starter.
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post #6 of (permalink) Old 10-02-2006, 10:32 PM
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Re: Exhaust Questions

On my 78, I have the stock manifolds, with exhaust ending somewhere under the bed. It only gets driven when it snows, rains a lot, or there's a home football game, so I really don't care about noise. It has straight pipes until about the middle of the bed, then is cut from where the muffler's fell. Rather loud, but as stated above, it rarely gets driven

On my 86, I have the stock "headers." They work good, flow excellent, and haven't really messed with any electrical. IMHO the stock "headers" flow really well for being stock, and they're just as long as manifolds. Then I have true duals until the "stock" exhaust exit, behind the rear tires on both sides. It's pretty quiet because it's stock mufflers and everything, but the Super 40's haven't came in yet, so it's still basically stock.....and the exhaust exit looks mean with my 10 inch drop rear bumper, with whips on both sides.

Sorry for the long and late reply, but I just got time to look through some old topics.
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