KUKACABRA

Whats up everyone? Im new here and I just bought my first Nissan. Its a 2017 Maxima S, deep blue pearl, black inlay 18" rims. I went from a 2003 Tahoe to this little road hugger thats got some getup and go. It shocked the hell out of me on the test drive, its a sleeper all day. Now the Question, I'm not to happy with the factory speakers. I just bought 4 Cerwin Vega 6x9's that are 4ohm. I never thought to check the 2ohm 6x9's that are already in it. Will swapping them without putting an amp on em kill what bass I already have? The factory ones beat pretty good but don't have any tweet. I'm trying not to put an amp on them cause as we all know, one thing leads to another and its gonna be amps, subs, new head unit, cap, so on and so on. Im not trying to do that to this car, any thoughts and comments are appreciated, thanks.