The majority of the "true cats" (aka - without pods) will "hop" between 50 and 80 MPH. The cats WITH pods do not "hop" at any speed.
However, the true cats are much better in rough water, or so they tell me.
I own a Spectre 30 with twin 300XS outboards and mine will "hop" between 55 and 75 MPH if I don't use the tunnel tab or if it's calm out. No big deal, just accelerate thru it or slow down. Runs awesome in rougher water.
I'm sure others will add more.