is it restrictive?

I mean it flows more air on stuff like the IHI kits, and the prime problem is your turbo running out of puff
 
cupra-neil said:
Im not to clued up on these things so i dont know, but ATP make a better manifold for the Golf/Leon, supposed to have better air flow, increasing more bhp gain?

on a std K03? I doubt it.
on higher flow setups yea, possibly, but not just total flow, but evenness of flow. (equal cylinder filling etc)