i had the JWT and then the typhoon, and then i modded the typhoon.
in short:
JWT = more noise - down side lots of heat soak, loss of bhp
Typhoon = slightly less noise than the jwt, but marginal, without a dyno its difficult to say, but i reckon i suffered less heat soak with the k&n felt like stock air box fitted really.
modded typhoon = i fitted mine with an apexi cone filter as it gives the best gains but the most engine protection when it comes to filtration. also its a dry filter.
more noise, felt bit more responsive. but this is all butt dyno, so not official.
at the end of the day, your fishing around for the difference of 3-5 bhp, which makes sweet f all to the drive of the car.
if you want more noise get something like the JWT, or do a modded typhoon.
if you want bhp bragging numbers for the pub, get an 06 air box, or an airbox conversion kit, and drop a good panel filter in.