SPEED DENSITY CHECK VALVE DIAGRAM

[speedytang]

Any Subaru dealer has restrictor that work or put NOS pill in the line.

[JPJP]

Or....if you are handy do what I did and make your own! I just got a piece of scrap nylon rod about 5/8" long and drilled the hole. Make sure to pick a diameter rod that will fit well inside the tubing so the vacuum/boost must go thru the drilled hole and not around the rod.

There is your restrictor. Now shove it inside of the vacuum tubing.

Just remember when you decide to freshen hoses to get that restrictor out and reuse it or the map sensor will see boost like I did earlier this year.