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post #1 of 3 Old 02-20-2003, 04:46 PM Thread Starter
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exhaust question

I have a 4.2 and I want to know if this engine needs back pressure to run. I always see cat back systems that promise hp increases but I'd like to know how and why.

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post #2 of 3 Old 02-20-2003, 04:55 PM
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Less restriction=more horsepower. It's true that too little backpressure will hurt your torque, but unless you're running open headers, I seriously doubt that you have to worry about that. I actually ran a conventional exhaust system with no cat and a low-restriction muffler for a while and felt a nice increase in power, but my girlfriend *****ed about the raw exhaust smell so I put a low-restriction cat on it and it cleaned up the smell nicely with very little decrease in power.

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post #3 of 3 Old 02-22-2003, 08:26 PM Thread Starter
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Thanks for the info. Also if anybody knows what is special about those cat-back systems. I've just got a cat with a glasspack behind it. Would any of those help or are they just more mufflers.

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