ha, i just posted this on another forum:
so i called Borla just to see what's what on the mazda 3 exhaust. turns out the speed 3 exhaust, which is available is axle back, not cat back, per they found no performance gains with the cat back. odd thing is, it's still $700+, at least directly from their site.
i then asked about the regular 3, and they said they'd have more information in 4-6 weeks as they are doing some R&D on the car. they aren't sure if it's going to be catback or axleback yet.
just thought i'd pass this info on. Borla is probably the only other brand of exhaust i'd look at other than CS. i had Borla on my '06 and it was stellar.