[c2wak]

Hi Guys,

 

My car is going into a local "Exhaust Doctor" whos making me a Catless Downpipe on the 21st, i was wondering what size people are running or in fact what diameter the big brands are?

I would guess 3.5 split into X2 3"?

[RS3Dell]

Hi Guys,
 
My car is going into a local "Exhaust Doctor" whos making me a Catless Downpipe on the 21st, i was wondering what size people are running or in fact what diameter the big brands are?
I would guess 3.5 split into X2 3"?

Have a look at Miltek, Scorpion,HG motorsport or APR to see what size & configuration they are using mate.

Dell.

[c2wak]

thanks Dell, yeah i looked at Miltek they say its Pipe Ø: 3.00" (76.20mm) *

I was thinking the joining pipe would be wider then down to 3 but it doesnt state.

[RS777]

If you go onto the youtube Iroz 3 part turbo thread they talk about a bigger diameter downpipe they make. They do a standard replacement size like Milltek and a larger size, but I am not sure if they mention how wide. maybe a quick email to them as a potential customer because it apparently has some benefits.

[RS3Dell]

c2wak

 

To be honest Miltek & the like have done there R&D into the down pipe size for a stock turbo & even a decatted stock one works very well.

 

Miltek down pipes are used by people on there tte500 turbos without causing a flow problem.

 

The different between my decatted stock down pipe & a aftermarket one on my tune is about 5bhp !

 

Dell.

[c2wak]

Yeah doing this purely for sound really cause i know that 500bhp from a map is amazing. But get what your saying, i will just get him to follow the same sizes.

[silky16v]

stock downpipe with gutted pre-cat is more than enough for stock turbo setup

 

save your money on the over priced crap from miltek and use it towards a FMIC

[RS3Dell]

stock downpipe with gutted pre-cat is more than enough for stock turbo setup
 
save your money on the over priced crap from miltek and use it towards a FMIC

silky.

A man of my own heart 👍

Dell.

[c2wak]

Does the FMIC make much difference over stock cause I have been wondering the best mods for these cars. So far the only restrictions are:
1) Secondary Cats - FL doesnt have these anyway, they were replaced by 2 small silencers at the rear before the back box. Had these removed already.
2) Primary Cat - Cat Bypass or as you say bashed out cat internals. I have already gone for a custom Decat so i have the original one to go back on when i sell it.
3) Intercooler - Forge or AirTec ( Will get one of these too if you recommend it with what i have already

4) Its been mapped but if the intercooler can be justified in the gains vs not having one, i will get the map tweaked.

Does the upgraded Spark Plugs and High Flow Fuel Pump come in here without upgrading the Turbo?. I just want to get the most out of the stock turbo having it running optimally.

[RS3Dell]

Does the FMIC make much difference over stock cause I have been wondering the best mods for these cars. So far the only restrictions are:
1) Secondary Cats - FL doesnt have these anyway, they were replaced by 2 small silencers at the rear before the back box. Had these removed already.
2) Primary Cat - Cat Bypass or as you say bashed out cat internals. I have already gone for a custom Decat so i have the original one to go back on when i sell it.
3) Intercooler - Forge or AirTec ( Will get one of these too if you recommend it with what i have already
4) Its been mapped but if the intercooler can be justified in the gains vs not having one, i will get the map tweaked.
Does the upgraded Spark Plugs and High Flow Fuel Pump come in here without upgrading the Turbo?. I just want to get the most out of the stock turbo having it running optimally.

c2wak.

My 8P is running all off the above to get the max out of the stock turbo.

Im using stock plugs but changing them at 10k instead of 19k.

The stock IC isn't up to it once remapped.

Forge IC & Autotec HPFP fitted.

Dell

[c2wak]

Thanks alot for this I just ordered an airtec and crash panel as aparently if you don't you need to cut existing which sounds a pain. I also want to put it back to standard if I need to. Had an airtec on my focus rs mk2 and was spot on.

[Hal]

From a pure design point, it is necessary for the downpipe to take the exhaust away as quickly as possible from the turbo, so the theoretical diameter is the same as that of the turbo exhaust port.

 

It maybe has little advantage in practice, but I like the Scorpion downpipe as it branches into two immediately after the turbo, compared to the longer single [restrictive?] run of the Miltec. However the Scorpion is trying to fit a lot into a small space and I have had rubbing issues with it.

[c2wak]

Fortunately I went with a 3.5" from turbo directly to twin 3" all the way to centre section and it's spot on even if overkill has plenty flow.

[Callum66]

Spoke to MRC about this on Thursday. Doug reckons that he would like a decat with a four inch entry and a single pipe for as long as possible. His thought was that downpipes that transfer into two pipes too quickly sound tinny. My plan is to get BCS to make a downpipe as soon as they can organise it.

[c2wak]

Is it possible to have a 4" pipe connecting to 3.5" turbo outlet? Surely that's too big. Would need to be 3.5 which is the outlet of the turbo then taper into 4". Or am I being thick. I can video mine once my back box is replaced it definitely doesn't sound tinny it's deep and growly. That being said I'm not a professional he knows what he's talking about but could be difference is negligible

[DUB]

Spoke to MRC about this on Thursday. Doug reckons that he would like a decat with a four inch entry and a single pipe for as long as possible. His thought was that downpipes that transfer into two pipes too quickly sound tinny. My plan is to get BCS to make a downpipe as soon as they can organise it.

This could be interesting. I had a turbo back bcs powervalve on my Golf R 👍

[RS3Dell]

Is it possible to have a 4" pipe connecting to 3.5" turbo outlet? Surely that's too big. Would need to be 3.5 which is the outlet of the turbo then taper into 4". Or am I being thick. I can video mine once my back box is replaced it definitely doesn't sound tinny it's deep and growly. That being said I'm not a professional he knows what he's talking about but could be difference is negligible

 

c2wak

 

Most aftermarket down pipes step down from 4"/100mm to 3.5"/87mm  The OEM down pipe on my 8P turbo were the V band fits is 4"/100mm.

 

Check out Ebay for 2nd hand down pipes & your see for your self the size difference with the OEM & aftermarket down pipes.

 

 

Dell.

Edited by RS3Dell, 15 April 2018 - 05:26 PM.

[c2wak]

c2wak

Most aftermarket down pipes step down from 4"/100mm to 3.5"/87mm The OEM down pipe on my 8P turbo were the V band fits is 4"/100mm.

Check out Ebay for 2nd hand down pipes & your see for your self the size difference with the OEM & aftermarket down pipes.


Dell.

Ah ok thanks for this. It was more a question statement than a smart arse one btw I'm new to it all.

[RS3Dell]

Ah ok thanks for this. It was more a question statement than a smart arse one btw I'm new to it all.

 

c2wak.

 

It wasn't taken that way mate.

 

Dell.

[c2wak]

c2wak.

It wasn't taken that way mate.

Dell.

That's cool. Cause am not one of those lol. Thanks your advice and help always appreciated mate.