I tested a 1.9pd mk5 golf on the dyno, did direct back to back runs with a pipercross panel vs a k&n induction kit and there was nothing in it performance wise, induction kit was louder and did sound rather nice.
Intake temps with the bonnet closed were a fair bit higher with the induction kit.
A good quality map is my advice, the 105pd will easily map to 155bhp with an extra 70ft/lb.