Secondary cats removal

5.0 V10 50v biturbo - 571 bhp
rs6_sid
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Re: Secondary cats removal

Post by rs6_sid » Sat Mar 19, 2016 11:15 am

Interesting to know , anyone know how hard it is to remove the whole downpipe might get both cats removed as I imagine there primary is a huge bottle neck in flow a bit like on the 2.0 tfsi. might see if bcs will build a large downpipe kit for our cars
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marknjayne
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Re: Secondary cats removal

Post by marknjayne » Sat Mar 19, 2016 2:49 pm

from what I hear the engine has to come out to do the primary cats

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IanH755
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Re: Secondary cats removal

Post by IanH755 » Sat Mar 19, 2016 11:37 pm

The sub-frame can be dropped to get to the downpipes.
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Re: Secondary cats removal

Post by Ceveman73 » Sun Mar 20, 2016 11:54 am

How long does it take to fit downpipes then, if the subframe is dropped?

I'm deliberating between various models of exhaust from Germany for my RS6, and have found some 3" downpipes at reasonable cost on ebay.de.

Anyone know if there's any need or benefit to have a full 3" system, vs a 2.75" one? Even 2.75" is a combined diameter of 5.5" which seem more than enough for 750-800bhp. My GTR ran a 3.5" system at 680bhp, and was fine.

Thoughts?
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Re: Secondary cats removal

Post by TomRS » Mon Mar 21, 2016 2:05 pm

Ceveman73 wrote:How long does it take to fit downpipes then, if the subframe is dropped?

I'm deliberating between various models of exhaust from Germany for my RS6, and have found some 3" downpipes at reasonable cost on ebay.de.

Anyone know if there's any need or benefit to have a full 3" system, vs a 2.75" one? Even 2.75" is a combined diameter of 5.5" which seem more than enough for 750-800bhp. My GTR ran a 3.5" system at 680bhp, and was fine.

Thoughts?
3" downpipes is enough to max out the turbo's so should see you close to 800hp, however you will be limited on torque due to the gearbox, and if you then go down the route of re-inforcing the box you mays well uprate the turbo's etc which is when things spiral! my best advice for bang for buck is just go with a secondary cat delete and a nice 2.75"/3" cat back thatll see you as near as dammit (depending on engine health) 730-750bhp and around the torque limit of 1100nm.

I debated going down the route of a full 3" and another remap to see 800/1100 but its an awful lot of money and effort for not a lot of increase in power. 50nm and 60ps... not worth the 3k+ cost for a full 3" and another map.

all up to yourself of course!
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Re: Secondary cats removal

Post by Ceveman73 » Mon Mar 21, 2016 3:26 pm

Good reply, thanks. So is there any difference in results from a custom 3" vs a 2.75" out-of-the-box system like the Milltek? Will they give the same gains at this power level? Off the shelf is a lot easier than going custom, but don't wanna mis on on extra power if there is some to be had by going bigger!
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IanH755
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Re: Secondary cats removal

Post by IanH755 » Mon Mar 21, 2016 5:21 pm

For bigger power cars (900+) they seem to be universally 3in. In fact I don't think there's any in the running 2.75in DP's at the minute (could be wrong).

With the German eBay downpipes make sure they actually deliver to the UK (even if it says "Europe" in the Ad) as the package is too long for Parcel Force who do the UK part of the delivery. This causes the seller massive issues, meaning most don't ship to the UK. I had this issue with KWE last year and ended up being refunded later on the same day I bought them.
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Re: Secondary cats removal

Post by pcorpe » Mon Mar 21, 2016 10:59 pm

nope sorry, went for a secondary cat delete and map all at the same time, oddly some ARB's got fitted also ;-)

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Re: Secondary cats removal

Post by Golfather » Tue Mar 22, 2016 2:01 am

3.5" FTMFW 8)

Image

Image

Image

TomRS
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Re: Secondary cats removal

Post by TomRS » Tue Mar 22, 2016 11:19 am

WOW! thats mental!

Why did you go 3.5"? seems a bit big?

And as for off the shelf vs custom its all about the noise, with a custom 3" (2.75" is an odd expensive size) you can tune the noise to how you want with boxes/resonators etc.
Personally for the price of an off the shelf milltek i'd rather put that into a custom job from a good exhaust place.
2014 Mercedes E63 AMG S
Wrapped in OceanShimmerBlue | MSL Stage 2 – 736Bhp/876ibft | Weistec Downpipes | K&N Large Filters | 400mm AP Racing Fronts/DS2500 Pads | Centre delete | H&R Springs/Link bars 30mm |

Gone but not forgotten :smile_smoking:
2010 Nissan GT-R SVM 680R
2010 RS6 C6 Avant Stage 2 730/1088nm

marknjayne
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Re: Secondary cats removal

Post by marknjayne » Thu Apr 21, 2016 6:21 pm

my secondary decats have been on for a few days,sounds so much better now and no dash lights (stage 1 map only)

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leet
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Re: Secondary cats removal

Post by leet » Fri Apr 22, 2016 6:25 pm

marknjayne wrote:my secondary decats have been on for a few days,sounds so much better now and no dash lights (stage 1 map only)
Which decats did you get? Did you fit them yourself? Don't suppose you got a fitted pic?

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Re: Secondary cats removal

Post by marknjayne » Fri Apr 22, 2016 7:05 pm

no fitted pics but this is a pic of the cats and the decats
Image
Image
Image

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A20LEE
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Re: Secondary cats removal

Post by A20LEE » Mon May 16, 2016 1:18 pm

Can anyone answer the question of, does fitting bypass pipes to remove the secondary cats put an engine light on? I've bought the same Supersprint bypass pipes and wondering whether to fit them or not. Will be a long time before the remap happens

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Re: Secondary cats removal

Post by rtd » Mon May 16, 2016 2:53 pm

A20LEE wrote:Can anyone answer the question of, does fitting bypass pipes to remove the secondary cats put an engine light on? I've bought the same Supersprint bypass pipes and wondering whether to fit them or not. Will be a long time before the remap happens
no engine light lee.
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