Alpine doesn't use removal keys.
Did you use the metal housing that came with the hu?

I don't think that the Alpine KTP-445 Power Pack will improve the sound dramatically. I would recommend to put some new tweeters in the a pillars. Add a crossover and level them with the fader of the hu.

Some examples:
Hifisystem des Crossfire Blackline aufrüsten - HIFI und Multimedia - Chrysler-Crossfire-Forum - Das Forum für Crossfirefans
Welche Soundanlage? - HIFI und Multimedia - Chrysler-Crossfire-Forum - Das Forum für Crossfirefans
Mein Hifisystem im Crossfire - HIFI und Multimedia - Chrysler-Crossfire-Forum - Das Forum für Crossfirefans