@HiOctane
it all depends on the environment you use the car in and how you use the car. in PK we have a dusty environment and therefore we have to clean the filters more oftern since they get filled with all sorts of particles.
my suggestion would be to clean the (aftermarket) filters every month to ensure the car is running 100%.
I have nothign against (so called) "performance intakes" since they do improve throttle response and can increase power too but since they are not too good at filtering fine particles there is no real benefit since you'll have to change the oil more often and excessive dist in the engine can cause premature wear of the cylinder walls and a buildup of dirt in the intake.
the final choice is yours but i'd suggest you use an OEM filter and spend the money on something liek plugs or spark amplification (MSD type unit) instead.