F20 - 125i Audio Upgrade

Howzit guys,

I need help. I have recently bought a 125i F20 (2013). With this being my first BMW, and with a family history of many BMW's, looking at the audio system wasnt really of "top priority" as you kind of expected it to be of high standards... I was sooooo wrong!

My moms 2008 Polo TDi has better audio that the F20. So i've been looking around and it seems there are options, but, there is only ONE option avaible from BMW and that is the Alpine kit, R12k +... Im told its not worth it? Iv heard it myself and it doesnt sound bad, but R12 + for essentially a mid and split?

Some of the options include the Ground Zero 3 way kit, coupled with an Amp, and another without an amp. the question is... MP... will you void it? Im not lookding for stupid amounts of bass and number plate rattling, i just want good clean quality audio, nothing "fancy" And i know as a rule, it makes sense though, cutting wires and tapping into them voids MP and warranty. Can anyone shed some light? What can and cant you do? If you use a harness (similar to the Parrot), will that void? If anyone knows someone i can maybe even speak to please shed some light.

Thanks in advance guys!