Can't load the link. Might try and find that on yt - those rallycross engines are mega. 600 odd bhp I think.
Anyway... Your best bet is an open cone filter intake like the ITG and Revo ones. The standard intake setup does a good job of muting a lot of the turbo/dv noise, so swapping over for an aftermarket jobbie will amplify things. Quite a few people actually find these intakes too loud for their taste, but I'm guessing it's just what you're after.
A remap will help too if you haven't had one already - more boost = more noise.
I doubt you'll ever get the car to sound like a rallycross car, but a decent intake is a start.
