MBC=very slight chance of spike, if it's done properly.
Other things need to be changed when raising the boost to keep it safe. Just raising the boost to 15 psi isn't going to do a whole lot. Increasing the boost with a computer like the ones FWD Performance sells is good because they change other parameters like fuel & spark tables, fan schedule, and spool time. Opening the exhaust & adding a K&N will do more than increasing boost only.