The Mégane II Owners' Club

I am very unhappy with my meganes sound and as a studio engineer/musician i'm looking to upgrade but times are hard and I know nothing about car audio so what would you recommend to change first? and what to change to?

Im looking at the alpine ida- whatever model headunit, they all look the same but pref iphone compatible.
and for speakers the obvious Pioneer TS-Q131C. but on a budget and these are expensive so any other suggestions?

Thanks

speakers first
then head unit/stereo
amp/sub if required

i have the old sony series in mine, but you end up with door pocket water problems due to depth