well for 550 max, you could get yourself a nice DD 3515 , or if you plan on getting more power down the line and if you talk nice enough to your local DD dealer you can mayby get a dd9512 for 550ish, mayby a 15" if your nice enough
edit:
all of these suggestions are worlds better than some "type r's or L7's" , ive heard type R's and owned L7's, i've thus moved onto digital designs //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif