i own a classic, 1979 to be exact and this car was ment to have 3 speakers, two 6x9's in the back and one 4x10 in the front, now this was just a thought that i had. many home theater systems have 5 speakers plus a sub, two subs if you got the money, now in my car i have tried puting speakers in the kick panels under the dash, and i have tried in the doors but there isnt a good spot to fit a 6-1/2 inch speaker but i had the idea of puting 2 7/8th inch tweeters on the corners of my dash or on the pillers and then puting a 4x10 in the middle of my dash on a separate amp bridged making it mono then i have my 2 rear speakers either on an amp or my cd deck depending on money and i all ready have my subs covered
aah the old center 4X10, I had one of those setups in my pontiac Grand Prix (1986). I threw 2 tweeters in that hole but it had the 3.5's on each corner of the dash, amazingly you couldn't tell the tweets were in the middle of the dash. I'de say putting 2 7/8in tweeters on the corners of your dash would be harder and look less clean than putting 5.25's or 4's in the doors. If you do go 5.1 setup that center hole will work perfectly for the center channel, or you can enhance your sound stage bye putting tweeters in that hole and in the a pillars, or dash corners.
yeah i dont really want to put any holes in my doors the tweeters im looking at are flush mount and well look preaty clean i had two 3" tweeter in the middle once but i couldnt stand the sound all on my right side
one problem i am having is i dont think that i can bridge my CD deck so i would hook up another amp for the center channel but the smallest amp i can find is 120W rms bridged and the 4x10 is 45w rms