Do not go over 17psi. The safe and long life psi is around 16.5 psi. After that...you are fair game for some major expenses.

 

the moter can take quite a bit of boost without issues... I've spiked at more then 20 psi. The biggest problem is that the stock turbo is really inefficent about more then 17 psi. The VF30's sweet spot is 17 psi, and i know a few people running 18 psi on a VF30.

 

remember, its a porsche engine!

 

The Subaru is no more a Porsche engine than a Ferrari engine. If you mean that it is a flat configuration LIKE a Porsche engine or a Ferrari flat 12 boxer engine you would be right.

As for boost 16-17 is tops for any kind of engine life. The internals are cast aluminun and they don't like extra heat expecially #3 cylinder. Running slightly rich is the best way to protect your insides.

 

I could not have said it better myself. The engine the WRX has was not designed to pump out tons of power so forcing it to do something that it was not designed to do with out proper mods is only asking for trouble.

 

Their is a difference between what you can do adn what you should do. You should run no more than 17 psi on stock internals to avoid the excess heat and cylinder pressures. You CAN run whatever psi you turbo combo will pump out. Don't confuse the two. Is either one wrong??? No, it's about the risk your willing to take. If you have the cash to rebuild and figure you will just push the stock internals until they quit then rebuild, then no big deal. If you are on a budget and don't plan on taking stock internal to the limit and have a margin of safety, then 16-17 psi is max. Life is full of choices, that's what makes it so great.

 

Nicely put Silver arrow.