Factory radios will do 4-8 ohms, no problem. Infinity makes some 2 ohm speakers (that read 3 on a meter), and they're usually no problem either. It wasn't uncommon in the past for GM to use 10 ohm speakers.
I don't think you'll have any problem at all, unless you decide to take the radio out to see if the amplifier is hot. Taking the radio out is a PITA.
Just remembered, I'm running non factory, 4 ohm, front speakers, and have been for 4 months. Zero issues, but then again, I'm mostly listening to podcasts..... at less than halfway (under 20).