dude i've got a magnaflow catback exhaust on my mazda 3 2.3L and love it!!! great sound, no throaty growl like a muscle car, but no fart can sound of a ricer with nothing but a loud muffler on the back. love it!! nice, deep humming sound go with magnaflow.
for induction i've got AEM cold air intake and love it as well!! great sound and torque difference, it really compliments the magnaflow. i had to get a water resistant filter cover for mine though, was having problems in the rain and car washes with the MAF sensor getting wet and making the car stutter and even shut off once.
what i'd recommend if ur worried about water at all, is go to protegegarage.com and check out the sealed carbon fiber box shorty intake here:
http://protegegarage.com/256-product-256.html
i'm considering upgrading to that.