I have an 06 model year. It came with an aluminum 21pitch. This was ok, I went down to a 19 pitch after the first year. I boat on a river so I kept it aluminum, and it's cheaper. A Stainless steel prop will help keep the top end speed. But aluminum gives more when you hit something. (I'm pretty new to boating, so anybody feel free to correct me!) It is a little deeper, so better at pulling skiiers out of the water. I didnt really lose anything on the top end mph either, time to plane is a little better as well. About the same economy and performance. Just a little more guts for the little 3.0L. I have even pulled guys out of the water wakeboarding that weigh 220?+ I dont know about the motor mount bolt though. Does it go into a threaded end, or is there a bolt on the other end to tighten it? Hope this helps!