Hi Nick
I'm also running an Alpine head unit (about a year old) on my JDM import, have changed the front speakers to some quality ones, the thing i've noticed though is that it's definatley not as loud as when the Bose head unit was in ()had to replace head unit in order to get radio reception), the question is why am I not getting better sound, not as loud, and when volume is up to near full it sounds like the bass is comprimised?!!! I have the JAP Sat Nav and computer still installed but the SAT NAV was updated with the Panasoic aftermarket kit. Hope this makes some sense?!!!