i have the 90" finish mower (at3590) on a 40 horse engine (tc40da) just went over a field of ragweed about 1 mph. cutting grass is easy at decent fast speed, i often slow down b/c the fields are too bumpy.. if you're regular in your mowing activity (like you're supposed to be, but who is? who only cut's 1/3 of the grass blade length off?) then you'd be surprised at how wide you can mow... not trying to 'answer' your post, just provide perspective...