from what ive heard and read, an aftermarket panel filter wont make much of a difference as the restrictions arnt in the filter itself, but if your going aftermarket, something like pipercross will do you well, you could probably pick them up from somewhere like awesome GTI as i think they sell them.
bluefin is well known, but its also known for being a very conservative map, so you wont get as much punch for your pound. ive got an evolve map on mine (also available with a loading box) on evolves dyno with just the map and a CAI it produced 319 bhp and similar figure for torque and later i had a milltek cat-back fitted and it produced 345bhp and 338 lbft on AMD Essex's rollers so its a very powerful map. another company to look at if your wanting a loading box is shark performance, i think they quote in the 320-330 range, but ive not seen any independent dyno graphs to confirm the numbers