Mazda engineered your engine to produce X number of horsepower from the factory and even with their careful engineering some engines do not make it past the warrantee period. The reflash pushes the engine a little beyond it's design parameters to produce a little more power.

There is obviously a very healthy design factor used by the Mazda engineers, but you have to understand that everything you do to your car including turning the key has a certain amount of risk.

In short, no guarantee but I've been doing this sort of thing for a lot of years and it is very very rare that any problems come from it.

-Michael