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Hello boys!

I wonder if removing the precats will make any difference in sound. Higher or different?

My setup is: Stage 1 tune, Milltec catback-non resonated and BMC-filters and sec. cats removed.
Couldn´t find any topic on this.

/Robert

Hi

You can hear the turbo's spool up faster, which gives increased performance.

IIRC it's 60hp to de-cat.

The tone/pitch doesn't change with a precat removal, just the volume as it gets a bit louder. However, removing the precats is an expensive job, especially if you (or garage you're using) snap a stud on one of the turbos taking the downpipes off, which is something that has happened a few times on here before.

For those after a sound change - The biggest sound change, for those who want to stick to an OEM exhaust size of 2.5in, is just to change the back-boxes which will change the overall volume but not the tone. Most folks however, like the OP, have fitted the slightly wider 2.75in Milltek which changes both the tone (a little deeper) and the volume (louder) but, again, for more volume the back-boxes would have to be changed. A few folks with higher HP cars have had to go for 3in or bigger pipes, which really drops the tome to a deeper one but can also add drone even with resonators fitted.

Mine are 3.5in de-cat downpipes to 3in de-cat non-res pipes with no X or H crossover (so two completely separate pipes from turbo to tip) with very small back boxes and I think no other RS6 sounds like mine does due to that quite specific combination, which is both good and bad TBH.

Thank´s a lot Ian! You always give good answers on this forum!!

What increase in HP and torque can I expect after loosing the precats with a retune?
Can you recommend where I can buy high quality down pipes?

/Robban

Hi Robban,

On stock turbos people on this forum have hit around 780-820hp with no cats at all and a stage 2 tune from MRC IIRC - Here's the MRC page with an almost identical spec to yours hitting those figures on the slightly older mapping software - https://www.facebook.com/mrctuning/post ... 599023656/

As for where to buy a set of de-cat downpipes, there are so many companies out there who claim to make/sell them, but at the same time there's a lot of cheap chinese-ium knocks out there, that I can't honestly give a good specific recommendation other than via MRC as thats who I got mine supplied by, but I've no idea who supplies them.

There's very few other people in here with aftermarket downpipes, mostly those with Stage 3 (900+hp) cars I would think, so I think you might get limited info I'm afraid.

Demand Engineering in Suffolk made downpipes for the first Stage 3 cars in the Country. They have the mold to make more.

I got mine done there, 3"

Superb place, Dan, the owner, is a great guy.

Thank's guys!!