I just opened the dash to handle 5.25" cdt audio coaxials, which sound amazing. Their 4" coaxial model will be available any day now, which I'll put in my rear doors (87 300td). These are both less than $90/pr. I got the 5.25's off ebay for $35, new. CDT also makes a component 4" system for about $270/pr. where you could mount the tweeter on the dash or pillar. One pair of these up front and a good sub would probably be amazing. You will want to add a 4ch bridged to 3ch for the speakers or some like set-up. No cutting or fabricating, amazing sound.