[jb84]

My budget is probably around £500.

Where can I get my hands on an Alpine OEM amp?

I've got aux input as well, so am happy to settle with Aux, CD and Radio - so it seems that recoding is all that should be done.

Next question: how much will the system increase in quality just by simply installing an Alpine OEM amp and recoding the head unit to HiFi output?

Thanks for all your help folks.
Cheers.