Safe boost level in modded wrx

I am posting this for a friend, we turned his boost up today from about 14 to 19psi.

His mods are untuned UTEC.....running a base map
K & N 3" Filter on stock intake tube
Up pipe/Down Pipe
Invidia 3"
Turbo XS standard boost controller

We have an AEM wideband and even with the boost spiking to 20lb the AFR reading was off the gague rich at WOT in 4th gear. Basically the whole purpose of me turning his boost up was to try to lean out the mixture @ WOT without actually getting into the ecu and adjusting the fuel maps. How much more boost if any would be safe for him. He always uses 93 octane.

What year WRX?

-Shane

2003

Your gains are minimal after 17-17.5 psi.. the stock turbo is pretty ineffecient after that point...

Set it to 17psi and get a good tune, you could use the TXS "Stage one" or "stage two" generic map as a template and adjust accordingly..I don't remember hearing of anyone running 19psi on the stocker for very long..

-Shane

you were hitting 19psi and wanting to go more on a td04???

you guys obviously dont know the limits on the stock turbo, 17-17.5psi is MAX anyone would even consider boosting

you are just blowing hot air after that and exponentially deteriorating your turbo