my engine makes this weird hissing sound when i step on the gas. at first i thought it was a blowoff valve, until i remembered i never installed anything to the engine. someone told me it was an airleak, but i dont notice any loss in power or anything. anyways, any ideas?

 

Sounds like leak in air intake (before throttle body), like when you remove the intake tube to the air cleaner box. If it was a vacuum leak I think you'd have drivability issues.

 

the weird thing is, i only hear this usualyl when i reach about 2000-2500 rpm