First of all, what are the specs of the subs? I would consider upgrading the stock speakers to even out the mids and highs. Most of the time rather than not, the bass over powers the speakers and sounds like crapola. I would also run another amp to upgraded speakers. But, if your on a budget i would first listen to the subs with the stock speakers. If it doesn't sound good then you probably should upgrade. But, first list the specs of your subs.