im looking to get sat radio in my 04 e55 not sure whats needed if anything ???

Sat Tuner, Sat antenna, sat tuner mount and you're good to go. The power and MOST wiring are already there. You need to remove the right trunk liner to get to the mounting location and the wiring harness. You will also need to include the sat tuner in the most ring and that is done in the communications bay at the front of the trunk.

If it's your first time it will take an hour or two, if you've done it before you can do it in less than 30 mins.

wheres the best place to get all the hardware?

Dealer for the tuner unless you can get lucky and find it on ebay. You need the SDAR For a MOST equipped car. E-class, S-Class, CLS, SL all share the same SDAR box. The mount is dealer only and the antenna can be sourced from Crutchfield.

http://www.crutchfield.com/p_220SUVA...irius+antennas

Or, you can go for a complete setup from here:
http://www.cartronics.com/MBMost.html?MBClass=E&VIM=1
Mike T.

Or by sourcing the tuner on eBay you can do the upgrade for ~$300

you don't need a mount. i put mine in and just sat it in the area where it needed to be installed. hook up fiber connection and power to the tuner. then follow fiber to the most ring and make sure you have the tuner included in the ring. mine was not and had to undo a fiber connection and basically make sure all those modules in the trunk are in a daisy chain together. buy the suggested flat antenna and sit it inside on the rear shelf (where the speakers are) run wire to sat tuner. antenna works through window....i have tint and rear privacy curtain.