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i have heard from a couple of guys their concerns over lack of back pressure due to my install of the slp loudmouths. i know that several people put long tubes and high flow cats and xpipes that have to create little to no backpressure. can this create a problem or is it something that you have to tune for? :headscratch:
 

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First off, can you hear yourself think with that exhaust? Second, yeah lack of back pressure can lead to a burnt exhaust valve. Any good free flowing catted X pipe, will give you sufficient back pressure with the right cat-back exhaust system, Mike. SCT Tuner.:bigthumbsup
 

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Interesting. How many burnt exhaust valves on a mod motor have you seen due to no mufflers ? I've had mine off since practically day one and no issues.
 

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Lack of some back-pressure means a better flowing exhaust. It can create a leaner mixture condition, unless corrected for. The better the exhaust flows, the more air/fuel that can be pumped through, and more HP made. It does not lead to burned valves, unless your computer can't correct for the leaner mixture.
 

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+1 me neither..
 

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If you were running a DD with open headers I might think about it. But with that long an exhaust system you don't have anything to worry about.
 

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I would be more worried about crapy gas. I have O/r x and not 1 problem.
 

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i have heard from a couple of guys their concerns over lack of back pressure due to my install of the slp loudmouths. i know that several people put long tubes and high flow cats and xpipes that have to create little to no backpressure. can this create a problem or is it something that you have to tune for? :headscratch:
i have run stock h-pipe with loudmouths , off-road h with loudmouths , and a powerhouse turbo with loudmouths so all in all 3 setups and about a years worth of beating on it never had a one problem with burning valves , someone is blowing smoke up your .........

and believe me if anyone can break a part it's me :helpsmilie:
 

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I've never seen this happen on a modular motor.
It can't happen!

That's an 'old mechanics tale' based on years of misinformation.

Yes, it would be a lean mixture that could lead to valve failure, but I do not believe that a 'lack of back pressure will burn valves.':nogrinner
 

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Sounds more like poorly tuned motors which are running lean burning valves. Whether or not that was due to a installing a free flowing exhaust is irrelevant, still goes back to the A/F tune.
 

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An absolute lack of exhaust components, such as running huge open headers, or no manifolds at all, could have caused burned exhaust valves due to the temperature differential between the cylinder temps and ambient air...but still highly unlikely.

Maybe somebodys uncle or grandfather ran a street-stock stock car with no manifolds, and burned a valve...just my guess.
 
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