I'd be surprised that a set could be so bad as a group of 4 that it would make way more racket.
KO2's are considered a very quiet AT, and not heavy.
Did you bump up to a size well over stock? Like 33"? Otherwise, I can't imagine you'd see a major drop in acceleration, etc.
It is 33”, but my previous set were also 33” Michelin Defenders. I still have the KO2s on and haven’t returned them yet. They are not bad as I may have sounded and the ride is fine. They are fine around town and up to 55mph speeds but once I get on highway speeds 70-80+, I can feel the difference in noise and I need to use the muscles in my right foot more.