Look at it this way - there are specific reasons why Mazda and Calloway set the boost at the level that they did. Is it possible that tampering with that will reduce the life of your engine? Sure it is. The fact is this; no one has YET blown an engine through higher boost, but also remember that no one has had the car long enough to truly determine what, if any, long term effects there may be. Check back six months to a year from now.
I personally feel that 10 psi on the MSP's setup is too much. Get an EGT gauge and/or an Air to Fuel Ratio gauge and monitor how rich/lean you run on fuel as well as temperature. Keep those ranges within acceptable limits and you'll be fine. It takes work, but that's why its called "tuning"
The higher psi you boost, the more air you force into your engine. You need the fuel to compensate, something that the ECU on all three variants of Protege does not do well at all. As stated above, the MSP has even been setup with a fuel cut (safety measure I imagine). What Flyin' Protege suggests for running higher than normal boost is an inline fuel pump. That along with their 02 signal modifier is enough to safely turn up the boost on my kit. $300
I've blown an engine, and let me tell you that it is no fun. Just be careful and tune smartly and you will probably have no problems.
Oh and one final thing - alot of people have posted in rather naive fashion that if the SRT 4 can have its boost turned up with an MBC right from the box, then goshdarn so can the MSP! Wrong. The SRT 4 has forged internals among other things, much much tougher than your average Joe Neon. The MSP has a Protege engine with a turbo. Mazda has stated in their racing materials that they believe the engine can safely handle 220 horsepower
at the crank. Look at the SpeedVision series Proteges - they replace an engine every four races. Something to think about.