I did the same thing BUT not all 6.5 will fit. You have to be especially careful with the depth. KRS, you put 6x9 in hatch back or coupe? I ain't done the rears on my GT yet...did component 6 1/2 in the doors, and component 3" tweeters in the dash. Just those two alone (without the rears) makes a HUGE difference in the quality of sound.
'92GT, 427" and '93 "LXVO" coupe