Anyone do Milltek downpipes with stock exhaust?

[UrS6]

How do you adapt them? What is the OD of the OE pipes for the slip fit?

[hahnmgh63]

My Catless Milltek downpipes just slid over the top of the stock pipes. I then just used a SS exhaust bank clamp similar to OEM to seal them.

Just went out and measure them. The O.D of the Miltek is 70mm and stock SE exhaust is 65mm. The I.D. of the Miltek is 66mm and change. So the Stock does slide right into the Miltek pretty good, not tight but tight enough that the Band clamps do a pretty good job of sealing them without an exhaust leak. I'm now swapping to Miltek all the way back so it will be 70mm the whole way.

[UrS6]

My Catless Milltek downpipes just slid over the top of the stock pipes. I then just used a SS exhaust bank clamp similar to OEM to seal them.

Just went out and measure them. The O.D of the Miltek is 70mm and stock SE exhaust is 65mm. The I.D. of the Miltek is 66mm and change. So the Stock does slide right into the Miltek pretty good, not tight but tight enough that the Band clamps do a pretty good job of sealing them without an exhaust leak. I'm now swapping to Miltek all the way back so it will be 70mm the whole way.
The US distributor told me that they would make up an adapter for me. I may or may not go full Milltek at some point. Do you feel that the downpipe's alone make a difference in performance?

[fukinavit]

The only restriction in the stock exhaust is the cats, other than that the stock exhaust is a very good system. The miltek only gives a deeper tone, with next to no performance increase.

[hahnmgh63]

As for the Downpipe question, no doubt it's and improvement. I have the Catless downpipes so I think someone on here had dyno'd somewhere around a 20bhp increase with gutted front Cats only so gutting them both has to do better plus the Miltek's are slightly larger diameter and have a slighlty better bend without the deep dimple that were on both or one of the OEM downpipes. As fukinavit mentioned, aft of the Cats there probably is nothing more to be gained, at least not without removing the Cats first and definitely has to be an engine flowing more air than stock.
I wish I still had my stock Downpipes to take a pic of the side by side as the Miltek's are definitely more restriction free than gutted stock downpipes but on a stock or just a flashed engine the Stock gutted downpipes are probably fine. I had my engine out at the time and was going to gut the downpipes and realized that I could get the Catless Miltek's from the U.K. for a good price so I went that way and am very happy about it.

[UrS6]

As for the Downpipe question, no doubt it's and improvement. I have the Catless downpipes so I think someone on here had dyno'd somewhere around a 20bhp increase with gutted front Cats only so gutting them both has to do better plus the Miltek's are slightly larger diameter and have a slighlty better bend without the deep dimple that were on both or one of the OEM downpipes. As fukinavit mentioned, aft of the Cats there probably is nothing more to be gained, at least not without removing the Cats first and definitely has to be an engine flowing more air than stock.
I wish I still had my stock Downpipes to take a pic of the side by side as the Miltek's are definitely more restriction free than gutted stock downpipes but on a stock or just a flashed engine the Stock gutted downpipes are probably fine. I had my engine out at the time and was going to gut the downpipes and realized that I could get the Catless Miltek's from the U.K. for a good price so I went that way and am very happy about it.
Great. Mine were out so I figured why not. I guess I'll sell my stock pipes and someone can gut them.

[BoiseAudi]

With the Catless downpipes does it throw a CEL? Work around for that?

[nubcake]

With the Catless downpipes does it throw a CEL? Work around for that?

Yes it will. Do a cat delete in your software.

[lswing]

With the Catless downpipes does it throw a CEL? Work around for that?

A mentioned, need a custom tuner such as nubcake, AMD, others.....

Off the shelf tunes like Revo, Euro, MTM, and maybe 034 really don't offer it or aren't around much these days.

Just hint, search on this site sucks, use Google and type in "site:rs6.com catless downpipe cel", or the like. Use back then forward browser button to get through spam links if you hit them.

[GmbH1]

My Catless Milltek downpipes just slid over the top of the stock pipes. I then just used a SS exhaust bank clamp similar to OEM to seal them.

Just went out and measure them. The O.D of the Miltek is 70mm and stock SE exhaust is 65mm. The I.D. of the Miltek is 66mm and change. So the Stock does slide right into the Miltek pretty good, not tight but tight enough that the Band clamps do a pretty good job of sealing them without an exhaust leak. I'm now swapping to Miltek all the way back so it will be 70mm the whole way.


I'v been thinking about doing catless downpipes on my RS like I did on my X5 M but was wondering what kind of labor was involved as far as the process and time? Thanks

[BoiseAudi]

all I have heard is its a PITA

[hahnmgh63]

Downpipes are a PIA but not impossible for the DIY'er depending on tools/shop available. Difficult without a lift but others have done it with Jackstands.

[BoiseAudi]

Cheapest I have found for either Milltek system is ebay coming from UK. Anyone find a better source or looking to sell theirs? I have my Milltek exhaust from my S8 and the RS6 already has SE exhaust with black tips. Was considering trying to make that work and just purchase downpipes and run straight back to the dual S8 milltek mufflers and attach my SE black tips..... Thoughts?

[hahnmgh63]

These are the guys that I bought my Milltek's from in the UK http://unit20.com/ the owner was on the forum here for a while but dropped off. There service/shipping is a little slow but with the weaker pound you can probably get a great deal, probably better than I paid yrs ago.

[BoiseAudi]

thanks, messaged them. Will see what pricing is and update it here for future buyer reference.

I am torn between Resonated exhaust so I can have decent sound but not obnoxious and installing cutouts for show. Or committing to the full non Cat downpipes and non resonated exhaust.

[GmbH1]

You could always start with the Non- Res Milltek with no catless downpipes and see what you think. That's what I did on my first RS and was very pleased with the sound of it. Now I'm wondering if I should try to just do downpipes with the stock exhaust.