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

[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