Kyle- I may be a bit late to share my input, but i'll give it anyway. I have a 97 854 so I think the speaker system is very similar. In the doors I installed Infinity Reference 5&1/4 (model 522i I think). It's the speaker with a pivoting tweeter. My other alternative were polk's of the same size. I wanted to reuse my grille w/o any mods. and they fit fine. i only need a speaker adapter kit so the wires from the car attached to the new speaker w/o slipping off. About 1 hour work total. I then installed the Infinity Basslink powered subwoofer in my trunk. My local Hi-tech Auto Audio did the install of the sub so i'm not sure of the connection method, but it works fine. No other amps needed. My SC-815 delivers adequate power but I know those speakers & sub can take alot more. I didn't need thunder sounds in my ride, just enough to vibrate the side mirrows when i'm crusin'.

Hope this helps.