Newb needs some speaker recomendations

[GDan]

I am new to this whole audio scene and i would like some opinions on what type of speakers to get. I drive a 2010 lancer gts and right now i have a Boston SPG-555 sub hooked up to a rockford t20001-bd amp with the stock rockford door speakers. So i would like to go way bigger, im not sure if anyones heard these subs before but is it possible to go over 140+ db with these or should i buy different ones. I also would like to know a good set of components to buy. thanks for the help