Boost will NEVER stay at just 5 lbs. It's addictive. Even if by some miracle the guy never had the urge to turn it up, a proper tune like Brian can provide will mke everything work perfectly well together no matter what size the injectors are. There's more to it than bumping up the fuel pressure adding a BTM and crossing your fingers.

And fmu's are junk from the get go. You said the guy had money, do it right or don't do it at all.