I had these recommended by someone on here. I am planning on purchasing them soon.
XT63II InPhase Audio
I fitted these about a month ago to re-upgrade my rear speakers. I'm the one who recommended them to you. You'll have to enlarge the predrilled holes for them to fit in the existing speaker support rods.
The trick to this, is to get the right holes by marking the holes on the XT63II speaker so that they are 11cm apart and get a drill and drill these holes to enlarge them. Once done you'll find that the speaker will fit/slot perfectly in on the passenger's rear speaker hole and support rods. For the driver's rear speaker hole it will not go down all the way but I've managed to get it in deep enough to apply all four screws and secure it. I then applied some foam material around to cover the air gaps and hey presto all done.
You may of course get alternative shallow mount speakers if you don't want all the hassle but I found sound quality and bass handling a big improvement from the JBL GTO 6528S which I had installed previously. So much so that I don't need to invest in a sub anymore