Drop your deck to 3" full throttle with a clean deck, if that doesn't do it I have no idea what to tell you. I have a good friend runing a 52" wildcat and it cuts great even with dull blades here in Knoxville. He is like most of us around here and gets a little of everything, fescue, bermuda, zoysia, and lots of crab grass. What dealer did you get it from?
Knowledge is knowing a tomato is a fruit, wisdom is not using it in a fruit salad.