
Take the money you were planning to spend on front & rear speakers, and put that total amount on better front componant speakers for the front.
Then have a subwoofer in the back and you'll be able to create a great sounding system.
The holes where the 6x9s were removed is a perfect place to let the bass travel from the trunk into the cabin.
But... that is just my personal preferance.
Some people love rear speakers, but I notice the time delay.
Some higher end HUs (head units), such as some Alpines and I think Pioneer Premiers models have time delay correction, which is very nice, although you are not going to see that on a HU below around $300.
Cliff