3 inch bore exhaust

[dewaryboy]

Just wondering what people's opinions are on running a 3 inch bore exhaust from turbo back on a vrs,I'm currently running stage 2 shark performance remap,fmic,Cai,3 inch downpipe with decat mated to blueflame exhaust,sai delete,few guys on golf forums are running a 3 inch bore turbo back exhaust sourced from USA and are saying they noticed a difference backed up by rolling road figures but I always thought 3 inch bore throughout was overkill for the ko3s turbo,what are people's thoughts?

[Bowders1]

Unless the car is on a bigger turbo I always thought 3" was too big and 2.5" bore is the preferred.

[dewaryboy]

That's what I thought to but the guys over on the golf and seat forums are still running the standard ko3s turbo and saw gains and I'm sure a couple were on r tech,s rollers.

[Bowders1]

That's what I thought to but the guys over on the golf and seat forums are still running the standard ko3s turbo and saw gains and I'm sure a couple were on r tech,s rollers.

But were the gains really the exhaust or just a different mappers rollers.

[dewaryboy]

To be honest I don't know if they just changed exhausts or changed exhausts and had there maps tweaked at the same time,I'm certainly a bit dubious of fitting a 3 inch bore exhaust to a standard ko3s turbo,think it's too big for a ko3s but the golf and seat boys are adamant it makes a difference,would need to see some evidence first.

[BrownBarge]

I heard the only difference is the noise it produces. 3" does seem excessive on a ko3s tbh

[Bowders1]

To be honest I don't know if they just changed exhausts or changed exhausts and had there maps tweaked at the same time,I'm certainly a bit dubious of fitting a 3 inch bore exhaust to a standard ko3s turbo,think it's too big for a ko3s but the golf and seat boys are adamant it makes a difference,would need to see some evidence first.

i just don't believe the exhaust would make a difference and i would say the 3" could rob power more than gain it on a K03s.

I would like to see the claims and how the results were undertaken.

I certainly would not change a 2.5" system over for a 3" on wild claims.

can think of better mods to do for same price

[Shadows Entity]

Don't even need an exhaust as you've got the turbo to create back pressure.

[dewaryboy]

i just don't believe the exhaust would make a difference and i would say they 3" could rob power more than gain it on a K03s.

 

I would like to see the claims and how the results were undertaken.

 

I certainly would not change a 2.5" system over for a 3" on wild claims.

 

can think of better mods to do for same price

That was my thinking,just wanted people's opinion,I will be sticking with what I've got until I have a turbo that warrants a 3 inch bore exhaust,many years ago I had a pulsar gti-r,replaced standard exhaust with a mongoose 3 inch turbo back and it made a big difference with no other mods,going by boost gauge I had gained an extra 2 psi boost by fitting the exhaust,turbo on that was slightly bigger than a ko3s tho,still miss that car in some ways lol

[LuckyvRS20vT]

So have I fuked up fitting a 3' downpipe then? 

Because it's 3' downpipe and decat section, then the cat back will be 2.5'...

 

Is that ok?

[dewaryboy]

3 inch downpipe is no problem,that's what I have into 2.5 inch from downpipe,I was asking peoples opinions on 3 inch bore exhaust,basically from cat back,but everyone's thinking is 3 inch bore is a bit excessive for the ko3s with is also my own personal opinion too but just wanted people's views as people over on golf,seat forums are convinced it's the way to go on a standard ko3s.

[P34RC3]

As far as im aware a turbo creates its own back pressure so 3" would be better than 2.5" as theres less restriction. If its non turbo than 2.5 would be max. I will be going 3" from the turbo back.

[Bowders1]

So have I fuked up fitting a 3' downpipe then?

Because it's 3' downpipe and decat section, then the cat back will be 2.5'...

Is that ok?

No a 3" downpipe is ok. From turbo back to centre section. That is just matching the manifold better with a mapped car.

As far as im aware a turbo creates its own back pressure so 3" would be better than 2.5" as theres less restriction. If its non turbo than 2.5 would be max. I will be going 3" from the turbo back.

That's true and yep from turbo back to system makes sense. But no point from system to end to have 3". It is not about restriction. I think you will find that the golf and seat forums are talking about a 3 downpipe and not a full 3" system.

The most restrictive part of our exhausts are the downpipe and std cat. The best gain is to replace those. So yeah a 3" downpipe is ok alongside a mapped car.

But I would say don't replace all the way with a 3" system as not only will you have trouble fitting it and stopping it from hitting stuff along where it is routed, but they can over spool the tiny K03s turbo.

[dewaryboy]

No a 3" downpipe is ok. From turbo back to centre section. That is just matching the manifold better with a mapped car.

That's true and yep from turbo back to system makes sense. But no point from system to end to have 3". It is not about restriction. I think you will find that the golf and seat forums are talking about a 3 downpipe and not a full 3" system.

The most restrictive part of our exhausts are the downpipe and std cat. The best gain is to replace those. So yeah a 3" downpipe is ok alongside a mapped car.

But I would say don't replace all the way with a 3" system as not only will you have trouble fitting it and stopping it from hitting stuff along where it is routed, but they can over spool the tiny K03s turbo.

It's deffo a 3 inch bore full system the golf and seat guys are fitting,item number on eBay is 331225468074,they say it's tight over the back axle but with correct adjustment it doesn't hit.

[Jimbling]

My octie has a custom 3" from turbo back, it's mega loud but I havnt driven a car with just a 2.5" exhaust compared to mine. I will try get a pic up of it but it looks like Stevie wonder welded it up!!

[Bowders1]

It's deffo a 3 inch bore full system the golf and seat guys are fitting,item number on eBay is 331225468074,they say it's tight over the back axle but with correct adjustment it doesn't hit.

The item price is great worth getting just for the down pipe decat at that price and about £70 international shipping is still good.

You won't be able to use system back box as too short for the Octavia unless you extend it. Probably be able to route the system OK as there are many joiners.

But like I said 3" on a K03s is overkill.

Might be worth a punt to see what it is like as you could always sell in to the golf community probably for more than you paid for it.[emoji4]

[Shadows Entity]

that's really cheap.... like half the price of a cat back system

[argylevrs]

Ive seen a few people put 3inch exhaust on but they are on hybrid ko3s ie the k300 etc.

[Bowders1]

Ive seen a few people put 3inch exhaust on but they are on hybrid ko3s ie the k300 etc.

That's my point they suit hybrid and larger turbo's well.