on a stock evo when it hits max boost it tapers down to like 17lbs. when you take off in first gear the seems to have alot of boost but when it reaches that max boost point the ecu tapers it down to about 17 for safety precautions maybe check with your tuner and see if he did anything with the boost levels in the ecu.....

 

Well i was with him when he tunned my car and he didnt mention nothing about boost tables or settings but i can ask him ....but i will think that would happen if i was using the factory boost solenoid but im not so you think that will have some thing to do with it?

 

then i can almost gaurantee that you have a vacuum leak somewhere also i just remembered is that the evo tend to leak boost or i should say vacuum from the factory throttle body gasket and the throttle body seals so you might wanna check that. the only way to do that is to test the whole system so like everyone else said do a leak test. just pressurize it.

 

Well guy's leak test done and nothing is leaking so i guess i can rule out any couplings problem, but my boost keep droping at 6k ..im thinking now that what my friend told me about the wastegate its true cuz i dont see what else can be making the car to drop boost.

 

could be stuck open!