Today I put my 88spl on the muffs, ran it for like 15 mins. Overheat alarm went off. The peehole had plenty of pressure, it did start letting out hot water out of the exhaust after about 10 mins (thermostat opens?), I am not sure on how muck water pressure/flow it must release from the side exhaust holes. It did seem lower than it flowed last week when I checked. Is it possible that the muffs didnt allow enough water to get in? Is it better to just stick the lower unit in a tub? any help is appreciated. Let me add that i wasn't idleing when this happened.I am going to try again today in a tub, But I think i will still replace the stats Since there is 2 is it possible that one is bad?. Do I absolutely have to pull the head to get to the stats on my 88spl?