Car Audio Advice ... HELP?

Not sure exactly what advise it is that you really want. But when replacing speakers you have to keep in mind that round speakers are not going to distort as much as let say a 6x9. A 6x9 or 5x7 say when the b is being produced and the woofer is being extended the speaker will tend to twist compared to a round speaker. I would say buy a round speaker that will fit the opening that already exists in the car. If you ever want to sell the car you can buy cheaper speaker and take the good ones with you to your next car.