If that is what you want from a car?
You want displacement and torque and the 2.5 has not to much of either.
So my advice is trade it now on a big block something or other. Or learn to drive the lower displacement Boxster to the 9/10ths and be proud of your driving skills instead of the torque in the engine.
The link will help you understand just how expensive it is to significantly improve the Boxster engine. It also gives you an idea what a bigger engine into your car swap might cost. More than you paid for your car, I'd wager.
http://mike.focke.googlepages.com/itisn%27tfastenough