Are you not just going to change the mid bass and the tweeters in combination? Would not worry too much about the tweeter diameter--will need to customize the A-Pillar cut out for the specific component set tweeters once you land on the brand and model of the set.

__________________
GXP--Cool / 5-Spd.
TSW Nogaro 19" Rims, 245/40ZR-19 Dunlop SP Sport Maxx XL Tires, M/F 3" Exhaust, Side Cowl Panels, Side Skirts, Gentex Rear View Mirror, Stubby Antenna, Little Chromies, Momo Shift Knob, Hand Brake, & Floor Plates, Full Interior Reupholstery.
Stereo Upgrade: Pioneer AVIC-D3, Alpine PDX-4.150 Amp, MB Quart QSD 216 6.5" Speakers, 8" JL Audio Sub, XM/Nav Reciever, iPod Adapter, Bluetooth Adapter, Boyo Rear Camera, Full Dynamat Interior.