2.5" or 3" Turbo Back Exhaust for POLO? ANY RECOMMENDATIONS!

[robihe]

hey everyone, just wanted to hear your thoughts on the 2.5" or 3" Turbo Back Exhaust for POLO GTI's?
from what ive heard with these smaller engines there is a possibility of loosing some power if the exhaust is too big (3"). so which would have a greater gain the 2.5" or 3"?

[mikepologti]

2.5 is more then ample for the ko3s and k04. if your a bigger turbo build ie garret, then gains have been made with the 3'.

[robihe]

2.5 is more then ample for the ko3s and k04. if your a bigger turbo build ie garret, then gains have been made with the 3'.

however will i experience any loss of power if i go with the 3"? because if not, i may just stick with it for the deeper grunt! =D
by the way im only running the stock K03

[peedman]

3" dump and 2.5" catback sounds good to me.

[robihe]

3" dump and 2.5" catback sounds good to me.

hrm..so will i experience more gains with the 2" or 3" if im runing the K03 and i dont think ill be upgrading in future. my appologies if i appear to be repeating the question. id just like a better understanding and a clear answer. if they produce the same gains. Ill be going with the 3" only because
ill get a better sound from it.

[peedman]

i dont think there is any harm in going bigger, u want a less restrictive dowpipe so the gases can exit as fast as possible. that being said 2.5" might be sufficient for a k03 but with the price difference between 2.5" and 3" downpipe bugger all, i would get a 3" dumppipe.

[h100vw]

A full 3 inch system will be boomy. 3 inch DP and 2.5 system is a good compromise. I don't think there's a great deal wrong with the std system TBH.

Gavin

[noone]

There is a few threads on the dump pipe and exhausts. General consensus is that the dump pipe has a little restriction, but not a lot after that.

Full exhaust is not a good bang for buck mod. If you are after a particular sound, try the Polo UK site as they are more likely to have off the shelf systems and they've posted a few videos for your ref.

There was some talk of 3" dump loosing low end torque, but others with 3" have not had this issue... read read read, hopefully help you make your mind up.

[robihe]

There is a few threads on the dump pipe and exhausts. General consensus is that the dump pipe has a little restriction, but not a lot after that.

Full exhaust is not a good bang for buck mod. If you are after a particular sound, try the Polo UK site as they are more likely to have off the shelf systems and they've posted a few videos for your ref.

There was some talk of 3" dump loosing low end torque, but others with 3" have not had this issue... read read read, hopefully help you make your mind up.

i think this option might cost quite expensive as it needs to be delivered from UK + labour on top of that. The reason i going after the turbo back is
because of this group buy going around, so i thought it might be a good opportunity where i can make a few savings. =D
by the way could you post me a link of these clips, it would be good to see the sound of these thigns.

[fintelboss]

The diameter will have more effect on noise then power.

To take andantage of the larger diameter you need to tune it specificaly for that size. I have never seen somebody that reduced their exhaust flow restriction that then coundnt make more power after being retuned.

[Blitzen]

Both APR and Miltek do dump pipes and full exhaust systems... Both are available in Australia, and both are quite expensive... I know that 3 types of diameters were trialed by APR before they settled on the 2.75In DP... This was found to be the better compromise.

[Greg Roles]

hey everyone, just wanted to hear your thoughts on the 2.5" or 3" Turbo Back Exhaust for POLO GTI's?
from what ive heard with these smaller engines there is a possibility of loosing some power if the exhaust is too big (3"). so which would have a greater gain the 2.5" or 3"?

I've yet to come across any proof that back pressure is in any way useful to a turbo charged car other than for noise reduction. That said, the size of the pipe closest the turbo matters most, where the gas is hottest and most expanded. As it cools, the need for big pipe decreases. With nearly all the friction occurring at the pipe wall to gas interface, be sure to take into account welds, junctions and contours. With the highest restriction in an exhaust pipe coming from any mufflers and resonators, then from any bends, then from the length of pipe itself, I'd be looking at the system as a whole, rather than just going by pipe diameter. I'd reckon a 2.5" system would be fine for a stock turbo, and if anything, look at putting 3" free flowing ( jap style ) mufflers on it, and minimising the turns and bends as best you can. But it is hard to beat a dyno tuned and proven system, as it goes beyond "theory".

[Blitzen]

Here are products and video's for the Polo GTI fitted with a Milltek exhaust system...

Volkswagen Polo GTi 1.8T performance exhaust systems and high-flow sports catalysts

[Oneofthegreats]

I don't know anything about polo gti's, but know a tiny bit about 20vt & also various turbo setups.


For a car equipped with a turbo the size of a 20c coin, I reckon its way too much overkill for a full 3" system.

But as suggested, you can't really go wrong with a 3" dump pipe.

My own home built 1.8L with a T3 Saab turbo also has a 3" dump pipe into a full 2.5" mandrel system with a standard issue hotdog & turbo rear muffler & it doesn't feel like its restrictive at all
IE. Nosing over in the top end or feel choked throughout the rev range.




For interest sake.

A friends old 13B rotary made 280rwkw's on PULP with 15psi, through a 4" dump pipe into a 2.5" system, which wasn't mandrel bent either!!!!



I doubt any Polo will make that kind of power out here! So any bigger than a high flowing 2.5" system, dump pipe back is a waist.


But if you like your car to sound like its running through Milo tins like in "2 gay 2 curious", I'll leave it up to you to decide.

[Chuck]

hey mate..i left the stock DP and put a 2.5" cat back with small canon exhaust on it...sounds beefy enough without being offensive...350 clams well spent IMO