Thanks both for the advice, shame because from looking around these are the only 'package' installs i have found online and from the sounds of things they are both weak setups.
Makkan if i bought either the alpine kit or mob17's kit my problem is that i'm not able to fit it for fear of making a complete balls-up of things. the 3rd link i sent is just a very local supplier who i believe have a decent experience with fitting audio into e90s so perhaps it's worth me speaking to them about the alpine or DSP.
Anyone know if there are such things as decent mobile audio fitters to work on our cars (in UK)? I'd assumed there would be but google seems to believe otherwise :/