It was definitely a lot of work eliminating the rattles and sealing off the doors. One good side-effect of the deadening is that the doors close with a much more solid 'thud' than before; I'd recommend it for that alone. I didn't have to cut any metal, but had to notch the back of the door panel to fit over the speaker. 6.5" speakers can't compete with 8" when it comes to bass frequencies, which is what I was going for here.
I say 'decent' because my opinion now (these pics are over 10 years old), is that the noise floor in the car is so high that obsessing over sound quality is somewhat pointless. This setup got very loud, produced a lot of bass up-front and sounded amazing (when the engine was off). These days I don't even have a stereo installed... I guess the sound of turbos singing, wind roaring, and my own schoolgirl-like giggling is all the music I need.