I just don't worry about the problem.
My 603 (Knock on wood) has 239k miles on it and is running better than ever. I added a quart of atf to the fuel at the last fill up and that seems to make it run better. I run it up to 4,500rpm a few times a day and it enjoy's running 1/2 to 1 hour at a time before shut down. My commute to school is 8 miles on the highway and the rest on 40mph roads. On the highway I average 60-75 but go up to 90 once or twice a week. The way I see it as long as my cooling system stays in good shape, and my temp stays at or below 105C my head will be fine. By next summer my cooling system will be all new.