B8 RS5 4.2 FSI exhaust discussion - share what you know

4.2 V8 32v Naturally Aspirated - 444 bhp
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marzz
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by marzz » Mon Mar 18, 2013 2:18 am

sakimano wrote:Not looking to discuss which aftermarket catback sounds best, but rather I would like to know what the stock setup is like in order to gauge whether there could be some improvements had by addressing any potential weaknesses.

Interested in the following:

1. diameter of downpipes and catback exhaust sections
2. is there a crossover (xpipe or hpipe) in the catback section?
3. how many catalytic converters are there, and where are they located?
4. what is the setup for the manifold...is it a log style manifold, or short headers..or other?

The B7 RS4 had the following setup from the engine back

manifold - tri-y headers
downpipes - 2.5" downpipes that tapered to 2.36" just before it mated up with the catback
catalytic converters - 2 in each downpipes...pre-cat up at the end that mated up with headers and main larger cat down before the mate-up with the catback. Gutting out the pre-cats yielded strong gains for the car while retaining the main cats and their ability to help a car pass sniffer emissions tests. You could also DIY it for free, so this was a great mod. Main cats were very good and flowed well.
catback - no crossover, with a resonated section. 2.36" diameter on the exhaust

As I mentioned above many RS4 owners found gutting the pre-catalytic converters to be a great source for efficiency improvement. The next level of performance gains to be had involved larger diameter exhaust and downpipes. 2.75" was the choice of MTM in EUR and JHM in the US, and we have seen very strong power and performance gains from cars with the 2.75" setups. Other companies went with a repeat of stock size with changes including the relocation of/deletion of catalytic converters or the addition of crossovers or adjusting the flow/shape of the exhaust. These stock sized systems mainly yielded sound gains and modest power gains.
have gone through about 10 versions of my exhaust so any questions feel free ...

RS5 manifold: squashed 4-1 shorties with massive cat right after, so one cat (integrated with headers) vs. B7 two cats

Image

down pipes: 2.5" with resonators

best gains: resonators and centre muffler delete, X-converter located in down pipes or instead of centre muffler (KLine, HMS, SuperSprint, APR), design shared with B8 S5 and RS4

if you are keen there are new RS5 headers available from KLine (engine drop unfortunately)
my ones are due to arrive today, that's how they look like:

Image
marzz - my RS5 build
Image

bam_bam
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by bam_bam » Mon Mar 18, 2013 12:37 pm

marzz wrote: Image
SEXUAL.
No matter where you go, there you are.

HYFR
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by HYFR » Mon Mar 18, 2013 12:56 pm

I'm running Supersprint front and centre pipes, removes centre resonator.
I pulled 432PS on dyno with it
No dyno before unfortunately

ITG filters going in should get me another 5PS?

toddcc1
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by toddcc1 » Sun Jan 05, 2014 4:30 pm

HYFR wrote:I'm running Supersprint front and centre pipes, removes centre resonator.
I pulled 432PS on dyno with it
No dyno before unfortunately

ITG filters going in should get me another 5PS?

I'm having the center resonator and front cats removed, is there a difference in sound with the muffler valves opened/closed?

Nickyboy
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by Nickyboy » Sun Jan 05, 2014 8:28 pm

Yes. I have the mod you mention above and it can be very quiet with them closed and awesome when open. Start up is quite loud as well.

Valves open at around 3,500rpm so can get drone at 88mph.
2014: 8V S3, Scirocco (mistake)
2013: B8 RS 5, 3.0T S5 coupe, B8 S5 cab - temp, B8 S4 avant
2011: 2.0T FL Octavia VRS
2010: 1.8T Octavia VRS

mark758
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by mark758 » Mon Jan 06, 2014 2:28 am

Hi sakimono,

I spent some time looking into possible performance improvements from exhaust changes on this car.
I didn't conclude there was a product out there I felt confident gave any sort of value for money.
Plenty of noise options though :)
From Milltek's published product dimensions they have used the same main pipe dimensions as the B7 RS4 for the RS5 - 60mm.
Capristo claim an increase of 13.5 bhp at 8300rpm with dyno plots that look very smoothed.
Not convinced I would even notice sub 3% power increase doing those revs.
Most reputable manufacturers seem to be steering clear of any bhp increase claim at all, even more so than they did for the RS4.
Having experienced two remapped cars from 2 software companies I think performance vs dollar isn't going to be from a nice simple pipe upgrade.
Be interested what your research reveals 8)
2013 Ibis White RS7¬
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kos11-12
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Re: B8 RS5 4.2 FSI exhaust discussion - share what you know

Post by kos11-12 » Thu Mar 10, 2022 3:46 pm

Hello guys,
Sorry to revive this thread.
I am new to this community, I just both an RS4 b8 from 2013.
marzz, if ever you fitted your catless headers, I will be very interested to hear if it made a significant improvement to the torque and power.
Best wishes
Konstantin

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