i am planning on switching out my stock speakers for some Kenwood - 6-1/2" 3-Way Car Speakers from bestbuy, i drive a 95 mustang convertible, so there isnt much room...but i was thinking of putting subwoofers either in the back of the rear seats because there is a gap there when the top is on, or i could put them into the truck mold...my question is is a 400w amp good enough, the sub i found is 200w max, and the speakers are 180w max...thank you very much