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DP: to Flex or not to Flex?

Old Jul 13, 2007, 03:22 PM
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DP: to Flex or not to Flex?

Kinda torn on what would be a better DP to get. I remember on other car forums hearing about people with a solid DP have problems with the bolts that attach the flange to the hot side break off under the vibration of the exhaust movement and engine movement. In some cases I seem to remember hearing about engine bays catching fire when the DP broke off and the 1600 degree exhaust gasses started blowing out into the engine compartment.

So my question is what opinions do you all have about solid DP's vs ones with a flex section? Seems the sold pieces may be easier to manufacture and a bit less expensive, but at the same time, you see lots of solid ones being sold by reputable companies.

Suggestions?
Old Jul 13, 2007, 03:24 PM
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i never had a flex pipe on both my downpipes. NO PROBLEMS.
i had a RMR and now a RNR...the RNR is shinier so i used that.

Last edited by Bom's Evo; Jul 13, 2007 at 03:26 PM.
Old Jul 13, 2007, 03:25 PM
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Flex pipes are for losers. Get an all stainless steel mandrel bent DP and you'll be fine. They won't break.
Old Jul 13, 2007, 03:39 PM
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thanks for the info guys. still reading about pro's con's of 70mm vs 3 inch

Old Jul 13, 2007, 04:19 PM
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Through a few dsms and a couple Evos, I've always went for the flex pipes. I figure its better to bend there than at the o2 housing or manifold if something happens to hit it or you run over something. You can even coat the flex section in most downpipes. btw - I've never had any break.
Old Jul 13, 2007, 04:26 PM
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Most Evo owners go with no Flex, best down pipes are with no flex.
Old Jul 13, 2007, 04:59 PM
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Originally Posted by romogst
Most Evo owners go with no Flex, best down pipes are with no flex.

That doesn't really make them better guy. Your response sounds like some Chinese proverb or something . Everyone gets one without a flex because thats mainly what you see - Buschur, RMR, Megan, DC, Espelir and I can keep going. I'm sure theyre all excellent products and work very well on the track.
Old Jul 13, 2007, 07:34 PM
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Had a BR downpipe with no flex for over 2 years now and its been on and off plenty of times with no problems just dont use crappy bolts.
Old Jul 14, 2007, 08:49 AM
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I have RSR , not RNR or RMR, no problem so far, stock bolt work great, does ever so slightly touch my ACD, flex pipes cause disruption in exhaust flow, called eddies which create unecessary backpressure....let it flow....catless *solid* Dp is the way to go, if you get pulled over just tell them "there was no place to install a cat!"
Old Jul 14, 2007, 08:54 AM
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The biggest difference is only whether or not the downpipe retains the stock spring bolts. They provide some dampening under torque and high load. Flex sections are designed to be used for the same purpose without the stock spring bolts.
Old Jul 14, 2007, 08:57 AM
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<~~not using stock bolts with springs but strong grade 8 bolts and it works fine
Old Jul 14, 2007, 09:33 AM
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Originally Posted by sonicnofadz
Flex pipes are for losers. Get an all stainless steel mandrel bent DP and you'll be fine. They won't break.
based on what?
Old Jul 14, 2007, 10:21 AM
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i have a version 1 megan downpipe with flex section. i like it. my front mount has softened up over time and i get quite a degree of engine flex/torquing over. id rather my downpipe bend then put pressure on other components.

ive just put in a ams front poly mount... so hopefully that will limit the torquing over.
Old Jul 15, 2007, 01:31 AM
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stock downpipe flange (spring bolt) no need to put a flexpipe. Modified/upgraded downpipe needs a flexpipe. I had a turbo rsx before and had no flexpipe, my downpipe cracked big time.
Old Jul 15, 2007, 04:21 AM
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would seem to make the case for stiffer mounts and/or engine damper?? just for the extra safety of reduced engine movement with a solid pipe, especially if you didn't retrain the stock spring bolts??

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