When you run it in that barrel, leave the garden hose running into the barrel. That will add cool water to the barrel, causing it to overflow. The big thing is that engine will put out a lot of exhaust heat, and will warm that water quickly. So, keep the garden hose running to keep the water temp lower. Why not just purchase a $5 set of ears/muffs and run it directly off the hose?
I like the barrel too. Provides some back pressure to further test the motor....and its much quieter, you can actially listen for add sounds much better
My only issue with the barrel is my nice painted leg gets gooey exhaust on it!