Chewing is not as common in cats as dogs, but I had a cat that loved to chew. He is now 6 and has grown out of chewing on everything, but he does still like to chew. The first thing I recommends is to by some Bitter Apple Spray
http://www.thepetstoreonline.com/grbiaptadetr.html
This will help deter the cat from chewing on the wrong things. The next thing to do is give him something that he is supposed to chew on. I tried many things with my Levi, any of the cat chew toys he would destroy. He is a good chewer. He loved Kitty kongs, but would destroy them in one day. So I decided to try some dog chew toys. The ones that he loves best are the Orka brand by Pet Stages.
http://www.thepetstoreonline.com/pet...chew-toys.html
He likes the mini bone, but usually I have to hold it while he chews on it. So I bought the small Orka Jack. That sits on the floor & he can walk up to it any time he likes & chew. The plastic is better than the plastic used for cat toys, but doesn't have the strange rubber smell of some other dog toys.