1000psi is great for wood but remember that if you have a 1000psi machine you will not have that at the end of the gun. couple that with low gpm and this where people "mess up" and overcompensate for the machine and get too close. Getting too close with these machines will still scar the wood, specifically cedar. Best is to take Pat's advice and get a higher gpm machine that way you have the volume you need. Remember you are only rinsing, the machine should not be doing the work. For this you want volume so you can rinse and get on to the next job. We also lower our psi the same way by changing tips with larger orifice sizes. I do not recommend anything except the 40 degree or white tip for wood surfaces. For most cases being approximately 6-12 inches away from the wood reduces actual psi hitting the wood surface and will prevent scarring as well.