Both are 5.25" speakers with a top mounting depth of 2.25". I'll be using 1/4 spacers to get the depth at 2" so I can keep my stock speaker grilles. The speakers will be powered with a 4-channel amp later on. I'm kind of leaning towards CTX5 because I'm planning on getting Image Dynamics subs also. I would like to keep my speakers/subs the same brand. Which one would you guys recommend?