i have a loud hiss coming from under the hood when i step fairly hard on the gas. it sounds like escaping air from the wastegate. perhaps the n75 valve is messed up. i have checked all the intercooler hoses, all are good, the K&N filter is clean. i am planning to get an ECS race75 valve anyway, hopefully someone out there can give me some info!!

 

a few months back i had a broken vacum line. There was hissing coming from the engine, it also tripped the check engine light, otherwise i probably wouldnt have noticed it.

cost me $20 in parts and $100 in labor, should have done it myself

 

Do you have a boost gauge?

 

Follow the hissing noise ???