I'm wanting good tight sound out of this but don't need heavy eardrum busting bass. Can you guys give me tips on the parts I have and am looking at? This is going in an 08 Mazda 3 GT Sedan

What I have so far to upgrade from Stock are 4 Pioneer 6" x 8" 3-Way Speakers (TS-A6874R)

Here's what I'm looking at for amp and sub

MB Quart ONX4.80/500
500W 5-Channel Class A/B Onyx Series Car Amplifier (ONX80.4+500)

Pioneer TS-SWX310 Pioneer TS-SWX310
12" 1000W 4-Ohm Shallow Mount Subwoofer Enclosure

Is that overkill or will this give me what I'm wanting...should I just go for a shallow 10" pioneer sub?

 

why not convert the front speakers to a component setup and put a pair of coaxials in the rear and add a 10" or 12" sub... be a nice sounding SQ car...

 

If you really enjoy the sound of those Pioneers, it sounds as if you're on the right track. Be aware of the current demands of 500W of class A/B power though! They are very musical, but not efficient (you may have heat issues as well- plan for some space around the amp, if not a fan to help cool it)