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post #1 of 5 (permalink) Old 02-04-2006, 03:03 PM Thread Starter
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can somone verify this please?

i looked under my car and i see that the exhaust manifolds bolt into the cats and basically at the cats there's a degree bend. i see that as a major loss of flow and power. i want to get downtubes made to take out the cats and make a much smoother pipe, then i'll run it into two high flow cats in front of the muffler. i think it would make for a much better flowing exhaust.

i have 2 questions i guess

i only see two cats, are there only 2? what about this resonator i keep hearing about? i only see 2 cats right after the exhaust manifolds an a muffler

does anyone know about positioning of the cats? i feel like they should be closer to the headers than about 31/2 feet or it will be a loss in power or something. it's a thought.

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post #2 of 5 (permalink) Old 02-04-2006, 04:15 PM
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Leave cats in stock location.
You have oxygen sensors you really don't want to mess with.

Whether they are 1 ft from the headers, or 3 ft, it should not make a difference, especially if you get Hi-Flow cats. I prefer removing them if possible (emissions).

I do not know specifically for your car, but my car came with a resonator, and it has been long gone. Your car might not of come with one, so don't worry about it.

Now go get some exhaust.

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post #3 of 5 (permalink) Old 02-04-2006, 05:20 PM
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The exhaust on your XR7 has two cats just after the manifolds, with horrible bends going into them, as you mentioned. The large "muffler-looking" object mounted midbody is the resonator. The resonator is also a large restriction.

You can move the cats back a little from the manifolds/headers (whichever you decide to run), but they need to be close enough to "light off". Moving them too far downstream basically renders them useless from an emissions standpoint. Here are a couple pictures of some of my exhaust setups:

The first picture is of the exhaust on my DOHC 90 XR7. The cats are about as far away from the headers as I would recommend. Any further than that, and you may run into emissions problems.

The second picture is of the exhaust on my Splitport 94 LX. The cats are much closer to the manifolds on this car. The bends on the downtubes are still relatively sharp, however they are a HUGE improvement over the stock setup.


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post #4 of 5 (permalink) Old 02-04-2006, 09:08 PM
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The postioning of the cats from the headers is not real important. That is except on a OBD2 car('95 up). Try to keep the O2's as close to the engine as possible
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post #5 of 5 (permalink) Old 02-05-2006, 09:36 AM Thread Starter
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thanks guys, it's a help

rod, if you plipped your car upside down i swear i could eat off the bottom of it
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