Changing the ride plate can help you in different ways. Some can help you corner, some can help you plain out faster and ride different in the water. As far as intake grates go, on glass water they actually slow you down because of the extra drag from the foils in the water. However, in rough water they work excellent because it keeps the rear end in the water which is how we move forward. Its all depending on what the water is like mostly where you ride.
If your looking to get more out of it, you should consider a filter and jet kit. Cleans up the soggy midrange and gives much better throttle response and more top end. You could even look at a new prop, I've been told the stock 15/20 is excellent all around in the XP. Its all in what you are looking to get more of, acceleration? response? top end? or a combo? A prop is going to give you one or the other, not both. A jet kit will help with both.