Secondary cat delete - costs and issues?

[Doug_RS6]

I know the topic has been done before but I couldn't find this specific information.

Right I've got a mapped RS6 (stage 1) currently has a Miltek cat back system and all the standard cats in place. I want to remove the secondary cats and I am looking for info from those who've had it done or looked into it.

I've had a quote from a custom exhaust place of £300 all in to make up pipes and fit them. I believe it's mandrel bends or at least mandrel bends cut an welded into shape. I'm waiting to clarify. And o2 sensor brings welded in.

Firstly is this price reasonable? I think it's ok really. Although I had hoped less.

Secondly will I get an engine management light on?

Lastly if I get a light on do I need either an o2 sensor spacer or a remap. Would rather not spend the quoted nearly 2 grand for a map from an apparent specialist near me. I'll refrain from naming the place.

[welwynnick]

Make sure you know what your guys are going to do.

There are two cats on each downpipe, and you can only remove the forward cats that sit behind the turbos (and are difficult to get at).

If you remove the larger rear cats that sit behind the gearbox you won't be able to pass the MoT.

Nick

[Doug_RS6]

I thought that the secondary cats were the ones that run under the car. Not the ones on the down pipes?

[pcorpe]

I had the rear most cats removed by (the most excellent) MRC, along with a tune, ARBs, filters etc. not had issue on MOTs, and been through a few even at dealer. can't comment to price as it was all in.

[Doug_RS6]

Did they use an off the shelf pipe or make them?

[welwynnick]

Matter of interest - is there much space around the forward cats (for fitting bigger cats if you wanted to do it that way)?

[pcorpe]

They simply cut the pipes either side of the cat and fitted straight through replacements (the tube is straight, no bends etc)
I'd recommend a call with MRC, i was in and out in less than a day, sure it's not the cheapest mod, but to point Welwynnicks point you need to have confidence in the experience folks have, specifically on this type of car. Search the forum and I'm sure you'll find alternatives to MRC, it was simply the closest to me that gained my trust.

[ShazRS6]

I had the rear most cats removed by (the most excellent) MRC, along with a tune, ARBs, filters etc. not had issue on MOTs, and been through a few even at dealer. can't comment to price as it was all in.

Sorry about jumping the thread but how much difference did the ARB make?

I’m getting some H&R ones fitted atm along with peronautomotive 3” downpipes and hybrid turbos

Do the ARB make a big difference?

[IanH755]

Hi Doug, just to clear up the confusion here with what owners are describing as primary and Secondary cats -

Primary Cat - Quite small and situated at the top of the downpipes right next to the turbo (within cm's of the turbine). Very rarely removed, normally just get de-cat downpipes instead and it WILL fail an MOT with these removed.

Secondary Cat - Much bigger and looks more like a "traditional" cat and is fitted right at the bottom of the downpipe where the exhaust bolts on. These are what people remove all the time on C6 RS6 and it WILL still pass the MOT with these removed.



The cost from MRC for a secondary Cat delete is Approx £500 (says FROM £456 on their website - it will be more) and they were using a set of Supersprint bypass pipes available from here - https://www.supersprint.com/ww-en/audi- ... m-kat.aspx#!/

Supersprint Secondary Cat delete Pipes

[Doug_RS6]

Thanks Ian. That was my initial understanding of primary and secondary cat locations.

I did find cat delete pipes on that well known auction site but was unsure about the quality of them (see link if interested)

Contacted a place called pipe dynamics within reasonable distance of me and the quote I've had from them is the one mentioned earlier.

https://www.ebay.co.uk/itm/142692210504

[pcorpe]

changing the ARBs gave a much better result than i was expecting, i went H&R, was expecting to also need to change the DRC/Springs etc, but for me found just the ARBs gave the feel i was looking for so not gone any further.

[IanH755]

changing the ARBs gave a much better result than i was expecting, i went H&R, was expecting to also need to change the DRC/Springs etc, but for me found just the ARBs gave the feel i was looking for so not gone any further.

It was the same for me when I had the H&R ARB's fitted. It added just enough extra stiffness to improve the turn in and dial out a little of the understeer without harming any of the car's ride quality.

[pcorpe]

changing the ARBs gave a much better result than i was expecting, i went H&R, was expecting to also need to change the DRC/Springs etc, but for me found just the ARBs gave the feel i was looking for so not gone any further.

It was the same for me when I had the H&R ARB's fitted. It added just enough extra stiffness to improve the turn in and dial out a little of the understeer without harming any of the car's ride quality.

Fully agree, so easy to make things worse, or end up spending lots of effort and cash to end back where you started, it's a heavy bruiser, most of it at one end so it's never gonna be hatch-back style handling, but i'm happy as is, i might do small spacers some time for looks, but don't feel the need for lowering or stiffer springs etc, the return vs the impact doesn't feel worth it.

the other thing whilst on handling was how much difference winter tyres made, never tried before, but wow, in the right situations very surprised.

[Hadies]

Got my secondary cats removed about a month ago.
Cost 180 quid. Local exhaust place with a good rep.

[welwynnick]

Got my secondary cats removed about a month ago.
Cost 180 quid. Local exhaust place with a good rep.

Were they the ones behind the gearbox? Have you had an MOT test since then?