i was told 6x8 by the dude at best buy, i havent changed them out yet just have a couple competition subs in the trunk with a 1600rms amp. all the websites say that u can put either 5x7 or 6x8 in the same location. sonicelectronix.com has them listed as 6x8 thay also have some pretty good deals with 1 year warrenty (also have lots of name brands JL audio, infinity

, pheonix gold). check out caraudiodeals.com they're usually cheaper (mostly off brands

besides audiobahn and kicker) but u have to pay extra for warrenty. if ur looking to upgrade.