£200 for a fancy air filter that does naff all or £200 or thereabouts for a remap that does a bit more
No brainer IMO
Or do both!
I'd never spend that amount of money on something that gives you so little bang for your buck. I'd rather put it towards a decat pipe or some suspension mods
I'd better not tell you how much I paid for my Gruppe M then on my old car!