Thanks for the input. I'm thinking of bumping up the aft service to an annual event, right before the summer heat seems like a good time of year.
What is your solvent of choice to clean the filter with?

'02 Montero: OME suspension, ARB front bumper, homemade skid plates & spare tire Blitz can mount, extended diff. breather, K&N air filter, Optima Yellow Top, BajaRack, IPF lights, Goodyear Duratrac 265/75/16's, RUD 4x4 Grip chains