Hi all. Ive dropped a clanger buying some gt spec headers only to find out theyl actually hinder ne more then give me better performance at my current spec.
ive been doing some reading, at my current spec it seems most recomend porting the oem headers but use a 'harvey' up pipe. Now IM lead to belive these also come in different sizes for different specs. So... What do i need for best results and where do i get it from? Or just leave alone?

current spec is...
uk turbo my00.
pump, td05 16g, full straight through 3", 3" decat downpipe, cossy panel filter, upgraded silicone intake, new age top mount, ecutek. 1.4bar 330hp 280tq.

help and advice would be appreciated aaron