I see. The people at the audio shops would know that answer or would it be best if i went to a bmw dealership and asked about it?
Doubt the dealer would know much, audio shop would really depend on how good they are. I would ask around or go on Yelp for feedback. I had my car done a bit over a year ago, biggest shop in my town, they had just moved to a huge new location. They were still kind of clueless. They told me all my steering wheel controls would work with the module they had. Most of them do, but the track skip up and down don't. Every stereo shop I've been to they will talk the talk. So if you go in without doing research 1st they will probably be good enough at gabbing to convince you they know what they're talking about.
I've had stereos installed at 3 local shops and Circuit City, all did pretty poor jobs. Finding a quality shop that's not going to rip you off is a chore.
Yea looks like i just need front speakers, amp, and subwoofer. Any suggestions to get the most out of my budget? even save me some money if possible
This isn't ideal, while it can work, new speakers + amp + stock head unit can be disastrous. Years ago I bought 2 Alpine Amps, Infinity speakers and a Kicker sub and kept the stock stereo. It sounded horrible, seriously it was worse than with the factory amp. JL makes a product called the Soundsweep for this, but it's not cheap. YMMV but I dropped close to 2k on amps and speakers only to wish I was stock again. I had a Ford with the Mach system, and at the time no shop around here could do anything to fully remove it. You could always go this route and see, and if you're not happy upgrade the head unit afterwards.
http://www.google.com/aclk?sa=L&ai=...-CL441dsp-CleanSweep.html?XVINQ=DST&XVVER=CCC