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For those of you using aftermarket headers on the 944 NA or 968: have any of you had a flex pipe added between the headers and exhaust system? I see many vendors building their headers with a slip fit joint which seems to work fine with no leaks (their words), but I prefer flange and bolt connections. Would a quality stainless flex pipe welded in between those components serve to minimize chances of cracks developing? Please post pictures or links to what you've tried. Thanks!

wildcat077

I have a Stahl long tube header on my race car and i have a stainless flex pipe welded in on the section after the header collector, yes it does help in reducing cracks.
My exaust is all stainless straight through , no muffler ...

Sorry i can't post a picture , my engine is out and i'm currently building another one !

951and944S

If stainless is welded correctly and purged during the process it should be fine, otherwise weld joints can be brittle and compromised from the get go.

In automotive world in general, flex joints first appeared in FWD cars where the engine is mounted transversely and since the exhaust runs down the car to the rear at 90 deg to their outlets, engine torque puts more direct stress than a longitudinally mounted engine like in the 944.

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931guru

inside that mesh is a bellows.

Aivar88

i had my dansk exhaust two times almost left on road, dragging it along , welded flex pipe in the middle and no problems this far. what a noise this 3L makes without exhaust, wakes all the neighbourhood.

wildcat077

Forgot to mention ... my exhaust slips onto the header collector and is held in place with springs , not with solid flanges !
Even the half "ast " exaust system that came with the car had a flex in it, although it looked like it was welded in by a blind person ...

951and944S

LOLZ, once at Sebring a few years ago, a guy that travels with us from home and paddocked next to us had his RE header crack with the 1.5 hr enduro left to go.
One of my other friends had a mig welder in his motor home cabinet but no helmet. Couldn't bum one anywhere and he barely had enough time to get it back on as it was.

I found a spot peaceful all by myself and welded 2 6 inch cracks with my eyes closed checking after every 1 inch of stitching.

Didn't look all that bad to be honest.

Made it in time and he finished the enduro.

A month or two later we are unloading somewhere else, making small talk he says "I hope that header holds up"

I'm like dude, that was a temp fix....., you didn't replace the header yet....?

RL'er too....name withheld to protect the guilty.

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wildcat077

951and944S

You know as well as I do then that the best stories come from the track.
Some people here kinda hint sometimes as if "dude, everything isn't about racing"
But if you race, it sure as hell is.

Just a month or two ago at Barber, a special pipe from muffler to turn down cracked right at the muffler's factory weld.
Went down the hill to one of the biggest teams.
They push a guy forward and say he's the best welder they have.
I can already tell by his setting up......, I don't think so.
I tell him, "man I have used that same machine before, I can weld it if you are tied up"
"Nah, nah, I got this"
Umh, ok, well, he couldn't get a mig run longer than 2 seconds and kept acting like it was the machine.
My son is standing there and I mouth - "This guy aint no d@mned welder"
HE's shaking his head like "ssshhh, don't say anything..."



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SloMo228

I have a long tube header and stainless exhaust on my S, no flex joint. It's held together with V-band clamps. No cracking after a couple years of street use; I haven't tracked the car though so I don't know if that matters.

My view is that the exhaust is bolted to the engine and hung from the torque tube for the most part (except the very rear mounting), so it more or less can just move with the powertrain. I bought a flex joint when I was picking out materials for the exhaust system but ended up leaving it out for that reason (and I needed the space for a catalytic converter anyway).

screamin94Z

I added a stainless 6" flex joint to my exhaust when replacing the stock cat. I have the factory exhaust manifolds but it helped a ton by adding some flexibility in routing the piping. My stock setup had a steep upward tilt that caused it to make contact with the rear sway bar. I also haven't tracked the car, but very happy with it and no issues at all.

KevinGross

We just replaced the flex pipes in my Cayenne's exhaust, which had broken on both sides. This is a common failure. My conclusion based on this fun experience is that unless you have a problem needing solving with your stock exhaust, stick with it. The flex pipes just add a relatively weak component that can fail. Good luck!

993944S2

Pictures of my flex joint, with v-band welded to one side. The other end of the v-band is welded to my header.

H.F.B.

Sorry, I missed your posting. Better late than never. Here is my solution. Works fine!
Here is a link for further information --> catalogue.jpgroup.dk/pdf/Flexpipes.pdf