go all out. I got a 99 323 a few months ago and am waiting to do everything. I have a 5 channel amp, alpine type x components, boston sub, eclipse HU, the works. You'll want to rewire in the end, but it'll be worth it. I'll post pics of mine along with a DIY when I finally do it.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>