Go to a store and they'll recommend u the most expensive amp they got for sale. They'll prolly also recommend u to sell the speakers and buy focals and change the head unit and buy an expensive naki one.
Trust me, nearly every store did that to me and all I wanted was to get pods made for my doors to fit the speakers in.
Anyway, try www.caraudioaustralia.com
They got good forums for car audio info. You cna guarantee a quick reply.