I have to say that the Evans has worked for me. Ive never boiled with it but try to be careful of times when the bikes building heat. Ive done the neverending uphill rut when your stuck a gear high and cant get to the shifter or pushing the bike out of the swamp from hell. I dont let the bike idle for long either. It mat get hot but the coolant stays in the rad. Better than boiling it out and riding with no coolant. I was going to put a overflow tank on but it ended up being unecessary. I used it in my 08 from new so the cooling system was good to start with and air temperatures varied between freezing and 30 degrees Celsius. I could always tell when my bike was probably hot by when OTHER guys bikes were puking. The Hondas especially. +1 on the Evans in my 2007 yz450. You can tell when it's getting hot and just shut it down but I don't have to worry about draining my drinking water into the radiators to make it back 25 miles to the truck! Almost all 4 strokes overheat in tight conditions and they either puke the fluid into a catch tank or puke it onto the ground. I don't have a catch tank but the Evans acts like one. I can tell when my bike is too hot and know whether or not to shut it off or keep pushing.