311roadster

I went to a local audio store today in hope of obtaining information about replacement of my Bose system speakers with new MBQuart speakers.
This guy told me that I cannot change out the speakers since the Bose ohm ~ 2 and most MBQuart ~4 ohm. I don't know if I believe him since I have seen some posts about people replacing their speakers. Any help would be appreciated. I would rather not have to replace my head unit at this time.

Thanks