I highly recommend PDA, Inc. in Littleton. I've used them numerous times and have been 100% happy with their work and professionalism every time. To date, they've removed my system from my Land Rover LR3, installed it in my Subaru Outback, built a custom sub box for my Subaru, and replaced my dead Kicker sub with a new one. Believe me, I'm very picky when it comes to who will work on my car audio stuff, and I'm totally pleased with PDA. Their office/waiting room even looks like a doctors office; no tacky neon signs in the window or dirt bags tearing apart your car. Here's their info:
PDA, Inc. 8080 Southpark Lane
Littleton, CO 80120
(303) 761-6022