To get rid of the bass in your door speakers go to your audio store and have them install CAPS on the door speaker lines that will filter out the lower Freq. that will eliminate the bass and distortion from your door speakers...... cleans up the signal and only lets certain higher Freq through.
If I was you though I owuld take back the 5x7's an since you want some 8" for your back ledge just get some components with tweeters and crossovers...they will sound awsome....Boston just released there new 5x7 components they are like 300.00 bucks i think...and that will give you good bass... and treble through the doors...
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