I would think that you would want to run the boost at to at least the stock level of 14.5 PSI
stock boost pressure is not 14.5
if you have a factory subaru gauge install it may read that but it's not right. i put a GOOD boost gauge in the car before i put in a MBC and in stock from with just a intake the car pulls around 9 or 10lbs in 1st and 2nd...then in 3rd and 4th at hard roll ons it will still only go to 11 and spike to 11.5lbs in 5th. i had several runs on the highway and this is what i came up with. i did this because everone kept telling me it was running at 14lbs and i just could not believe that the factory would sell the car runing that much boost. has anyone else tested like this and came up with anything different? i don't think eveyones car is running at 14.5 and mine is not....again gauges can make a big difference so make sure your using a good one.