[RS777]

I thought I’d start a chat on the exhausts available and the pro & cons. This is what I found in sizes posted on Audizine:

Milltek = 3"
Uni = 2.75"
034 = 2.75"
ECS = 2.75"
APR = 2.5" (most expensive)
Cts = claims 3" but measure 2.5" (thanks RaudiRS3)
OEM = not positive, probably 2.5ish

To complicate things further Milltek have a 73mm and 80mm options for the RS3. Currently I have the 80mm version and after reading the above decided to use my new callipers to do some measurements. For those that didn’t know the system splits into 2 pipes for 2/3 the length of the underbrush and goes back to 1 pipe before joining the back box. I can’t say where the the above measurements are taken from but I can say the Milltek one like my 80mm option is the single rear pipe only and the twin pipes are in 70mm.
With all these exhausts it is clear there is a big restriction going from the 2 pipes to one when doing the math, even on the better 2 x 70 going to 1 x 80. I can see no one stays with 2 pipes due to room and probably complexity of routing.
I will measure the oem sizes at the weekend as I still have the Sports exhaust.

I did see Akropovic do a titanium exhaust but it’s smaller that the Milltek and £5400 + shipping.

[rs3_alex]

You're missing the EGO-X 3.5" from HG Motorsport, which I would argue (being an 89mm straight pipe once the valves are open) is the most highly performing and technically capable system on the market!

[RS3Dell]

You're missing the EGO-X 3.5" from HG Motorsport, which I would argue (being an 89mm straight pipe once the valves are open) is the most highly performing and technically capable system on the market!

a

The BCS 8P full system is quality without any drone,the straight through by pass valve opens on boost & British made to boot.

Dell.

Edited by RS3Dell, 04 July 2022 - 08:08 PM.

[RS777]

Thanks for the replies.

One thing I am adamant with is I will not be having the exhaust valves. Mine are rattling and no point buying new ones when I just the bypass wiring plug to and keep them open all the time.

EGO X 89mm sounds pretty good for airflow as most are 73mm on the single pipe section, which seems pointless when being fed from 2 x 70mm pipes.

[RS777]

Just had a look and it appears BCS only to the downpipe for the 8V and not the full system. This was the brand I had on my Scirocco R and I can say was very well made. Saying that the Ego x looks quality as well.

I have another contender for an exhaust named Eddy Brooke Racing in Oxford. They do bespoke exhausts for some high end cars and are focused purely on performance.

It’s good to get a topic going and get owners views.

[RS3Dell]

Stu.

One thing you need to take into account is that as the hot exhaust gases travel down the exhaust system it cools & contracts so the diameter can be reduced to a point.

Dell.

[RS777]

Stu.

One thing you need to take into account is that as the hot exhaust gases travel down the exhaust system it cools & contracts so the diameter can be reduced to a point.

Dell.

Stu.

One thing you need to take into account is that as the hot exhaust gases travel down the exhaust system it cools & contracts so the diameter can be reduced to a point. If someone was doing track days and running a bigger turbo there would be more heat after multiple hard pulls but not such an issue on the road.

Dell.

Yes I agree with you on that point. Probably would be better if these exhausts gradually changed diameter like F1 cars but I guess you are talking mega bucks for that.

[RS777]

Sorry that post went a bit wrong, doing some odd double quoting and it won’t let me edit it.

[RS3Dell]

Yes I agree with you on that point. Probably would be better if these exhausts gradually changed diameter like F1 cars but I guess you are talking mega bucks for that.

Stu.

The point I was making was about the design of the OEM system which one pipe goes into two pipes going back into one pipe.On the 8P at the turbo end its 100mm which also has the primary cat then goes into two 63mm pipes then after the 2nd cats go into one 75mm pipe onwards,the two 63mm have as much if not more surface area then the single 75mm back pipe but due to their routing it's not very good for flow compare to a single 75mm downpipe aftermarket one's.

Audi have already worked out that as the exhaust gases cool & slow down expanding enough past the 2nd cats that the pipe diameter can be smaller to suit the space that is available & probably noise as well

The 8v onwards have a similar but better design due the subframe having more clearance.

Remember the OEM exhaust has been designed around the factory tune & environment criteria.

Dell

[Rooferman]

The key to an exhaust on a forced induction car is to have the DP as large as possible, if you're getting a custom exhaust made then just go 3.5" from turbo back for max flow and least back pressure

[RS777]

The Milltek DP with no cat is pretty big so I’ve decided to go with Eddy Brooke Racing for the system. They design race exhausts all the time and already have the full spec/measurements for the 8v RS3. He stated they can build a bespoke exhaust to improve flow rate by a better Design and larger bore. Added bonus is a huge weight saving. Booked in for next month at Oxford, which will take a week to build and fit.

Edited by RS777, 08 July 2022 - 05:32 AM.

[flybynite]

The Milltek DP with no cat is pretty big so I’ve decided to go with Eddy Brooke Racing for the system. They design race exhausts all the time and already have the full spec/measurements for the 8v RS3. He stated they can build a bespoke exhaust to improve flow rate by a better Design and larger bore. Added bonus is a huge weight saving. Booked in for next month at Oxford, which will take a week to build and fit.

 

That's probably not a bad way to go and they seem to have experience on the VAG stuff. 

 

I am a fan of BTB as I have some of their exhausts and they are a work of art. Their flow is difficult to match. Problem is they only do other work in the motorsport off season and their real expertise is in BMW N/A exhausts. Very similar company in many respects to Eddy Brooke.