Is it possible to fit 6"X9" in the back speaker locations without having to do any cutting of any kind? My girlfriend has a nice set of Infinity Reference 6X9 sitting around from here old car and I would really like to use them.
nope. you're pretty much stuck with 6.5/6.75 unless you want to do some serious cutting and reconstructing of the speaker mount. plus you don't need big speakers in the rear, as the rears are commonly used for fill anyway.