Quote Originally Posted by matt5112 View Post
Head gaskets become a concern past that IIRC.
Quote Originally Posted by FoSHO99 View Post
You just want to be careful with timing, the higher you go the higher the cyl temps/pressure. In one season and on flat terrain you could have no knock, on another season and hilly terrain you may get lots of knock. If I didn't have a tuner I wouldn't run more than 18* year round and just change pulley sizes accordingly. Vice versa if you own a tuner, or you can play a little more.