I have been doing tons of research and making a list of maintenance that I'm sure needs to be done to my 02 yz426. Changing the valves being one of them. I plan to switch to the stainless set of everything. But is it even worth it to change the valves without changing seats? The valve clearances tighten up because of the wear on the seats don't they? Seems like the seats might be a necessary part of this equation to restart the process of shimming the valves if that makes sense. Is there a way I can replace the seats at home, I'd really rather not have to pay a machine shop to do it if changing the seats really is necessary.