Which bcs downpipe?

[Liamedition30]

Just after abit of advise, booked in at bcs with nige yesterday for downpipe and decat but still unsure about either 3" or 3.5". The car is stage 1 now with all the parts to go stage 2 after the downpipe. What's people's opinions?

[DANBOY66]

stock turbo 3" bigger than k04 3.5"

[CarlW]

Any particular reason why not to put 3.5" on a standard K03 GTI just out of interest as i'm trying to understand more about the exhaust side of things before i make a decision on what i'd like to do myself in the near future.

[DANBOY66]

from what i have experienced there is no point in the extra cost for next to no gain

my car made fantastic figures on 3" with sports cat (bcs) i did not see hardly any improvement fitting a 3.5" decat

[Paradox1]

Wouldnt it flow better if the whole exhuast system was 3.5 instead of just part of the downpipe?

Eitherway 3inch should be enough no matter what turbo your running(within reason)

[dan930]

What did Nige suggest?3.0 or 3.5?

[DANBOY66]

it will flow better at the top end but you sacrifice low down torque

like i said i was stage 2+ made 364bhp 405 lb/ft torque fitted dw intank pump 3.5 down pipe and decat and a runner flap delete

my car then made 375 bhp and 386 lb/ft torque and it feels slower due to making less torque the whole of the rev range not just at the top

since then i have fitted an anti serge turbo with clipped hot side wheel i am going back for mapping on the 5th of jan