In my opinion the front speakers are decent but the rear speakers are junk. A cheap replacement option is to obtain a set of OEM front door speakers (the tweaters in apex panels and the woofers in the doors) and put these in the rear doors. A better solution is to replace the rear door speakers with a pair of aftermarket component speakers (which is what I did, and later I added an 8" sub). I feel the high-mounted separate tweaters on the rear doors really improved the sound stage in the car. Since you already have a sub installed, you don't need extra bass in the rear, just better midrange and highs.