Hey there, i've just recently purchased a 1998 WRX sti version 5 and under none or little boost the car runs fantastically, but as soon as the pressure builds and the boost comes on, water flies out the radiator overflow. After the car has been driven it looks like it is bubbling in the overflow. The previous owner had done three head gasket checks and came up short. The only mod the car had was an external wastegate which i've taken off and is now running everything standard. Any ideas as to what it might be other than the head gasket? The temperature gauge is also sitting really low, mostly under halfway and on colder nights just sits at zero or a quarter. Oh and the car doesn't overheat, but I guess after a lot of boosting and all the water leaving the radiator it will eventually. And when I checked the radiator the water all looks fine, not murky or anything, and the oil also looks fine. Any ideas, suggestions, helpful or even not so helpful advise would be great! I'm keen to try anything at this stage.