I have been using these speakers recently in budget installs, and in my opinon they are the best in the market for the money. But be careful their prices range from £30 to about £50 so shop around to get the best deals.
They handle around 50W RMS which is more than enough for any head unit on the market, but for use with a high powered system you would either need 2 sets of them, or different ones.
They are 3-way speakers, so you can expect Warm punchy bass, balances mid-range, and clear trebble.
As with all 6x9's they are easy to fit into your car, so you will be on the road with your impressive sounds in no time.