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Originally Posted by USAFstevo
What are the number gain differences between high flow cats and test pipes?
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Not much. We're talking less than 5hp.
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Originally Posted by USAFstevo
How do I prevent my CEL from light coming on with either installed?
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You buy a brand that has a good track record. I have 6k mi on my ERZ HFCs and no CEL.
Quote:
Originally Posted by USAFstevo
Will it be 100% necessary to get a tune after installing test pipes? As from what I understand any tampering with the computer automatically voids the warranty.
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There is no need to get a tune after adding either test pipes or HFCs. The computer can adjust A/F ratios to keep things in range. The tune becomes necessary when you've done more than three bolt-ons (cbe, hfcs, intakes, headers). Doing all four can lead to lean situations and a tune is highly recommended by the tuning companies sponsoring this site.
Remember that test pipes have some negatives that may not offset the marginal hp gain over HFCs. 1) more rasp: HFCs have some, test pipes have more. 2) smell: your exhaust will wreak after adding test pipes. 3) bumper stains: the uncatalyzed exhaust can leave yellow tinges to your rear bumper that require some additional 'work' to remove when washing the car. 4) noise: test pipes will be louder overall than hfcs. 5) emissions: in states that check computer codes, both should pass as long as there is no CEL. If they use a sniffer, a HFC has a small chance of passing, test pipes don't have a prayer.
Hope that helps.