Not to be a smarty, but it's probably aluminum if possible. Can you post a pic of the front deck and a better description of why you want to extend it? Just want more space to move around, more storage, room for 2, etc?
My last boat was a tracker 165. I built a removable deck extension out of landscaping timbers, treated 2X4s, and marine plywood. I bought some outdoor carpet from lowes and covered it. Worked pretty good for what I wanted, but your project depends on what you need and how much you can spend...