larger down pipe on 1.8t ?

[gpk_gti]

Hi everyone,
Has anyone changed the standard downpipe to a larger more free flowing downpipe? I have noticed on other sites that there seems to be alot of debate about 2.5" or 3".
The car has middle muffler removed with a MTM rear box.
I have changed the turbo to the k03s and am waiting on my other bits.
I have been quoted $270 for 2.5" ceramic coated from tuffy in alexandria.
Any advice would be greatly appreciated

[fuzion]

Seb from Euromotive has 3" ones available. Apparently thats the way to go. i think hes bug racer on here.. get in contact with him would be my suggestion!

[Bug_racer]

I have 1 3 inch exchange here

[gpk_gti]

thanks bug racer,but what I really wanted to know is is 2.5" or 3" better?? I read on vortex that 3" can cause over spooling http://forums.vwvortex.com/zerothrea...49554#11249554
from what I can gather the k03 is more suited to 2.5" and k03s to 3" downpipe? whats your thoughts?

[h100vw]

I have a 3inch on my A3 with a sport cat and 3 inch system. The turbo will spool quicker as there is less restriction of the exhaust gases leaving the turbo.

The wastegate and electronics control the boost level the engine sees.

You could hear straight away that the turbo spins up quicker/earlier. It whistles nicely now. I have a big turbo planned which is why I went 3 inch over 2.5.


EDIT.
That vortex thread mentions certain chips and downpipes. So not the DP on it's own. Only incorrect code would cause the turbo harm.

Say chip X requests Y boost, knowing full well that the turbo could never spin that fast because of the restrictive DP. You now fit the 3 inch DP allowing the turbo to have a go at reaching Y boost. It may overspeed which is one thing that could damage it. I doubt that any 'off the shelf' code would cause this to happen.

[BLKMJC]

You'll get less more torque down low with the 2.5" and more HP up top with the 3". I went with 2.5" as I wanted to car to be more zappy around town where I do most of my driving, also GIAC recommends 2.5".

BLKMJC

[Bug_racer]

2.5 for torque , 3 inch for power . On a KO3 car Id stick with 2.5 but KO3's or KO4 use 3 inch . 2 3/4 is available but more expensive than a 3 inch

[VWEAPN]

does anyone know how much power gain there is with either a 2.5 or 3" dump pipe?
is it worthwhile?

[h100vw]

does anyone know how much power gain there is with either a 2.5 or 3" dump pipe?
is it worthwhile?

Very little, if any without changing the chip. The power delivery may change due to the turbo spooling earlier.

Gavin

[SoVeReIgN]

I have a 3" (courtesy of seb) and I can definently notice the difference.

It isn't amazing but its there, and the turbo spool sound is a little rougher/meaner too

[VWEAPN]

ah ok ye mine is GIAC'd, N75J,air box mod,
now i know theres a bit of a discussion here on whether to go with the 2.5" or 3".
what is recommended?

[VWEAPN]

ok i have read over the posts again sounds like the 3" is the way to go?

[gpk_gti]

do a 2 3/4 ,,,best of both sizes!!! thats what I have...

[h100vw]

I agree, 3 is overkill. That's 3/4 over std and an epic increase in cross-sectional area.

Gets calculator out

Gavin

std 2.25inch is 7.95 square inches in diameter.
2.75 would be 11.88 50% increase over std
3 would be 14 76% increase

You just couldn't make use of the extra flow IMO.

Gavin

[VWEAPN]

well i know the 2 3/4 is pricey due to its size, so im scrapping that one.
i will see what happens on the day, turning to 2.5"