MPI downpipes

[djtallrick]

Mounting This Weekend!!!

[TeKiZeRo]

Looks impressive!

[djtallrick]

$899 and they are in Miami

[SMOKE EM IF U GOT EM!!]

Anymore info on these?

[edwinm3]

another brand making these without the flex sections.

[catch]

Originally Posted by edwinm3

another brand making these without the flex sections.

my first thoughts exactly. While these are the best priced DP ive seen so far, it looks like people really want to see flex sections

[CaryTheLabelGuy]

Originally Posted by catch

my first thoughts exactly. While these are the best priced DP ive seen so far, it looks like people really want to see flex sections

Flex sections are likely not really needed with no Cats. The cats get very very hot as this is how they're designed to work. The "flex" section is more of an expansion joint. No cats, no expansion joint needed.

[edwinm3]

Flex sections actually take away unwanted stress on the turbo flanges by allowing exhaust pipes to move and expand with heat and/or movement of the rear pipes. They are definitely needed I would say. Don't really want any stress on those turbos possibly cracking or breaking them under all that stress.

That's a very long pice of pipe moving up and down and side to side under acceleration, turns, braking, going over bumps etc.

[mshab356]

Originally Posted by edwinm3

Flex sections actually take away unwanted stress on the turbo flanges by allowing exhaust pipes to move and expand with heat and/or movement of the rear pipes. They are definitely needed I would say. Don't really want any stress on those turbos possibly cracking or breaking them under all that stress.

That's a very long pice of pipe moving up and down and side to side under acceleration, turns, braking, going over bumps etc.

[Tiago@VRSF]

These pipes look nice but I have to comment on the flex section/expansion bellow complaints we keep seeing.

Originally Posted by edwinm3

Flex sections actually take away unwanted stress on the turbo flanges by allowing exhaust pipes to move and expand with heat and/or movement of the rear pipes. They are definitely needed I would say. Don't really want any stress on those turbos possibly cracking or breaking them under all that stress.

That's a very long pice of pipe moving up and down and side to side under acceleration, turns, braking, going over bumps etc.

The OEM N54 DP's have expansion bellows just like the M3/M4's and every popular aftermarket solution still does not offer an expansion bellow on their downpipe. We've sold thousands of sets without one flex section and have never had to warranty a single pipe due to a lack of expansion bellow.

There's cars with over 140k miles running our downpipes with no flex sections without any turbo/manifold/downpipe failures. The S55 catback offers more bracing than the N54's which should eliminate any doubt of the S55 possibly needing them.

[edwinm3]

Originally Posted by Tiago@VRSF

These pipes look nice but I have to comment on the flex section/expansion bellow complaints we keep seeing.

The OEM N54 DP's have expansion bellows just like the M3/M4's and every popular aftermarket solution still does not offer an expansion bellow on their downpipe. We've sold thousands of sets without one flex section and have never had to warranty a single pipe due to a lack of expansion bellow.

There's cars with over 140k miles running our downpipes with no flex sections without any turbo/manifold/downpipe failures. The S55 catback offers more bracing than the N54's which should eliminate any doubt of the S55 possibly needing them.

Sorry but not a risk I would be willing to take on this a very expensive car (at least for me). Trying a product and hoping it'll last and/or hoping it doesn't break anything could result in a very expensive lesson.
I'm not hating on any of the products out there, nothing personal, just my .02

[gtrsam]

thought those bellows were there for the heat from the cats? not really necessary

[edwinm3]

See this thread

http://f80.bimmerpost.com/forums/sho....php?t=1062586

[edwinm3]

If the issue is the heat coming from the cats, then how do you guys explain the NA cars not having the flex sections? Take for example the S65, they have front cats right after the headers and no flex.
No turbos=no flex. Yes turbos= yes flex.
Something has to give under heat and movement and it is the flex absorbing these vibrations and movements, you take them off and the turbos will be stressed "possibly" causing damage due to fatigue.

[AlpineE92M3]

Originally Posted by edwinm3

If the issue is the heat coming from the cats, then how do you guys explain the NA cars not having the flex sections? Take for example the S65, they have front cats right after the headers and no flex.
No turbos=no flex. Yes turbos= yes flex.
Something has to give under heat and movement and it is the flex absorbing these vibrations and movements, you take them off and the turbos will be stressed "possibly" causing damage due to fatigue.

Very valid point, although from my experience, with many high HP turbo vehicles, from big turbo STi to 850hp supra, I have never had "flex pipe" downpipes. Usually these are installed from the factory to confine to their specifications with the materials used. Aftermarket products typically use higher strength materials, different engineering specs which typically eliminates the need for "flex" sections. I could be wrong but I don't think that they are necessary.

[te37]

Originally Posted by edwinm3

Flex sections actually take away unwanted stress on the turbo flanges by allowing exhaust pipes to move and expand with heat and/or movement of the rear pipes. They are definitely needed I would say. Don't really want any stress on those turbos possibly cracking or breaking them under all that stress.

That's a very long pice of pipe moving up and down and side to side under acceleration, turns, braking, going over bumps etc.

Had a strait tube down pipe on my turbo 240sx car for a couple months and the exhaust manifold loosened up and the gasket blew, replaced the gasket and a down pipe with a flex section and never had any issues for the next two years. A lot of force moving and swaying about, the whole exhaust is on rubber exhaust hangers you don't want all that force swaying and forcing your turbos around.
It will act as a big lever.
Nick

[edwinm3]

Originally Posted by te37

Had a strait tube down pipe on my turbo 240sx car for a couple months and the exhaust manifold loosened up and the gasket blew, replaced the gasket and a down pipe with a flex section and never had any issues for the next two years. A lot of force moving and swaying about, the whole exhaust is on rubber exhaust hangers you don't want all that force swaying and forcing your turbos around.
It will act as a big lever.
Nick

exactly

[Jeff@TopGearSolutions]

A majority of manufacturers tend to think the flex sections won't make a difference or cause any issues, including some very reputable ones that have been in the industry for a while. That being said, if it really matters to the end consumer, there are a few options with flex sections now, like Active Autowerke.



They are priced competitively to the MPI option so it's really a no brainer.

[dapple]

these look just like the chinese copies that you can buy on ebay for $300, infact even the welds, position of lambdas and internal weld on the flanges look identical.

I have first hand experience of the chinese rubbish downpipes, they simply dont fit well at all.

http://www.kwe-racing.de/images/prod...ages/852_0.JPG

[tr_ms3]

MPI buys their downpipes from Shifteck, slaps a logo on them and then doubles the price...

[mike@x-ph.com]

We never heard back from OP . How did the downpipe install go?

[Marckymarc305]

Installed mine two days ago