My car keeps pressure in the cooling system even after sitting for a week or two. And when you run it hard the water blows out thru the cap. I have a catch can on it. I blew the heater hose two times then a head gasket because I still ran it. I was runnin 25lbs of boost in 4th gear with 11-12 degrees of timing but the car was at 22 with 9-10 degrees of timing. always ran 93 and had a little of 110 in there tonite. Also the thermostat I think was bad car ran at 205 but at nite it could run cold as 120 because boost cut for cold was 15lbs and it would hit boost cut until it warm up from running in boost. Just seeing if someone else had a problem like that. Its a z6 with a felpro head gasket, t3/t4 57 garett. Tune on NepTune by me with a 59300 cam. and eagles and srp.