Thank you for the reply. This is kinda what I thought.

2008 gt500 with a hellion twin turbo setup. So compound boost.

Besides the above kit the fuel, spark, intake mods are:

1) Kenne Bell BAP
2) Diablo Mafia
3) 1000cc injectors

The stock boost gauge reads zero and never moves. I have 19# of boost and my boost controller reads correctly.

My tuner is telling me the stock boost gauge will not work because of the Diablo mafia. Is this true or is it just his maf curves arnt correct? Also would the mafia cause a p1228 Dtc code?