My Miata is a 92 which I use for weekend driving and ~1 autocross a month. I have had a couple people drove my car and make note of somewhat poor braking. It has fresh fluid, SS brake lines, and no apparent vacuum leaks (did the engine-off brake hold, pedal doesn't sink). I haven't seen any pulling, uneven pad wear, or overheating rotors that would make me think I have a stuck caliper. The pedal is stiff on braking, it just don't have much bite. I am running the R4S pads in the rear, and Monroe ceramic pads in the front. My next step is to try upgrading the front pads and see if that helps.
I have been looking at the plethora of brake pad options on your site and am a bit intimidated by the numerous choices. I have done some forum research, but it seems like everyone has a slightly different favorite. The Porterfield R4S seem like a good choice, as they would match what is in the rear, but there are also the HP+, EBC Green Stuff, maybe even the R4, etc etc. I would go for the Axxis Ultimates on the basis of several glowing recommendations, but it appears they are no longer available.
I realize it's as much a matter of personal taste as anything, but what sounds like the best choice for me? Looking for good initial bite even when cold and low noise (if possible). Can live with a bit of dust.