07 and 04 mustang stereo systems

OK I've gave this some thought and here's what I've come up with. In the 07 1 of the mb quart qsd's up front and then build a narrow band crossover for two of the vifa's. One in the lower front doors and one in the rear deck. Along with 1 mb quart qsc213 in the rear deck. Then the rest will go in 04 mustang. Id like to put him a 6 1/2 in his front door but i don't believe he has room. So i'm thinking 1 qsd's up front and then 1 qsc's rear deck with qsc216 mid bass system in the rear deck also. Do you think if i make crossovers for the vifa's it will effect sound any. Being mix with mb quart speakers. Thanks for any help. Tim  

 whats the model numbers of the vifas? Are you considering minor custom install or simple swap out of the speakers? what about amplification?

Vifa's are # M18wn019-04. There base auto 6 1/2 speaker. Amp's I'm not sure what I'll buy. But I've always have had Kenwoods and probably will buy again. My son wants JLaudio subs and amp's. He has a good friend that had some and he realy liked the sound. I don't need mine real loud, but just want it to sound good. He's like his loud of course. I'm not sure if i should build the crossovers or just have madisound do them. That's where i bought them. I haven't built any before. But I've been to some classes and believe i could do-em. Also the 8 inch has the factory amp pushing it. Could i use it to push the vifa's or do i need to just get an amp to run everything in front and back ?   Thanks for your help. .   

I missed the custom install part . Yes I'll try and keep it as stock looking as possible. Tweeters will be mounted in a pillars. I made a 5x7 plate out of mdf for his and mine for 5 1/2's.  not sure where he'll put his tweeters. He might use the stock location, which is at the front corner of the door. I'll be making something for the 6 1/2 going were the 8's are out of mdf. Amps and crossovers will be in the trunk on both cars.       

Thanks for the help i really appreciate it.

Well here's where I'm at. I install one set of the QSD's in front of the 07. I put the tweeters in a pillars. 5 1/2's in stock location in doors. Just with that the sound difference is incredible. Next I'm installing QSD"S in back with a 6 1/2 mid-bass system. The 5 1/2's will be installed on side panels, tweeters will be at same height as front tweeters. Mid-bass speakers in rear deck. Ive been looking for some 8's to replace the ones in front doors. Is been hard trying to find 8's for it.  I did paint the tweeters and rear speakers to match interior color. So far it sounds killer. I probably wont have time to do rear install till next weekend. More as i go. My sons car he will be installing when he gets time from Navy. I'm not going to install any of the vifa's. We tried them and it didn't sound as good as the MB's. I'm also ordering a second mid-bass system for the 04 and a Kenwood digital 4 channel amp for the 07. To run all of the MB's.