Help i had the T replaced with a 3/16 mod and so was the restrictor. boost was great up to 17lbs.. but would spike like crazy. I decided to set everything back to stock the t and the restrictor now i get 9psi max.
I saw by the turbo there is a brass thing i think its th waste gate.. any how on one of the hoses i saw like a little barrel inside it which i decided to take out.. this was brass inside the vacume line. this is when i noticed this..
-i decided to put that little brass barel inside the vacume hose and still the same thing.
-is it supposed to have that?
-which side does the shorter vacum line go to (the wastegate or intercooler)?
thanks.. i notice my car much slower..

 

cool tried that and didnt work.. I only got 7 after that..
I decided to switch the hoses.. i put the shorter hose from the T close to the intercooler and it worked fine boost back up to about 14.5.. the long curvy hose goes towards the turbo.. who knows what the problem was..

 

I had the same thing happen to me after I removed my MBC. I never figured it out and just put it back to stock and took it in for warrantee repair. They told me they just replaced the restrictor and ran the lines the way they were suppose to run. I now have the 3/16th mod on and that’s it and it runs fine.

So double check that all your little hoses run the right way and you should be set. If you need help ask someone you know with a stock WRX to get the tubing right. They have to be same type and length as stock.

 

I'm currently having the same problem...

When I installed perrin's short ram intake, turbo inlet and I/C hoses, I thought I would change all the vaccum lines to red.... big mistake. For a while I was only getting 8 pounds of boost, untill about 20 different trys of hose combinations(sizes, lengths and restictors) I finally got 13 pounds of boost back, but now my boost is dying off at about 5500rpm????

If I get a mbc, will that fix the problem of the boost dying off? or just give me more boost untill 5500rpm?

 

there are some pics. that worked. i looked for the 3/16 mod and saw the pictures of the tubes.. the cruvy tube goes from the wastegate to the T the shortest hose with the little barel goes towards the intercooler side.. boost went back up to 14.5 sweet. i guess it does need that barrel.
make sure you have this setup.. i took the barrel out and got 9psi again.. so i put the barrel back in the hose. happy camper here..

 

I went to subaru, and the mecanic their told me the same thing, he even gave me a couple of new lines and the brass fitting. Then we took my car out with his computer, and tested to boost, and every run it got faster!!! everything is back to normal.

Thanks

Nitro