These are just terrible questions to ask--- one of the worst questions is "how many SPL will this hit"--- who can say? All cars and setups are different. It depends on the car, box, how well you seal everything, and how will you support 10,000 watts? You will need at least 2 alternators unless you are strictly burping at competitions, which you will need a boatload of batteries. It gets downright pricey to build a competition vehicle.
I would say at least 145db. What is your goal? To have a competition vehicle? Or have the loudest car in the town for listening to music?
