use 6'' in the rear and 6'' with splits in the front add your own style of sub woffer and your off. I have 6'' all round and 2 10'' subs sounds great but i'm upgrading to 6'' with splits in the front. 6x9's are for peoplr who dont want to run subs really. dont forget its not how many watts you have its matching the watts off your speakers to your amp run everything at its right power and it will work correctly