Rear Speakers

I have just fitted the Pioneer TS-Q131C in the front and moved the front speakers into the rear slots.

However, I can tell the difference and get an obvious better quality of sound coming from the front.

Is there any tips on what speakers would be best for the rear?

...stupidly I didn't try the Pioneers in the rear first?

Thanks
 
the back will have built in tweeters i believe called two-way, i brought TS-E1376 because they were the same colour as the TS-Q131C, but i believe there are cheaper ones
 
in the front you want components (these are seperate mid in the door and tweeter in the dash) for the rear you need co-ax (co-axial) speakers. These are where the tweeter sits in front of the mid on the same axis. Both are 13cm.