I can't comment on that particular product, but I've got some 4 inch steel corrugated pipe that I'm gonna try running from the grille to half-covering my K&N. They supply some pishy little 2-inch thingy that's supposed to help, but it's probably of little use. I'm just taking it a step further. I might also use some as a heat sheild, pop-rivveted to a simple framework.
Gearbox + MOT to do first though....
