Map sensor problem?

[01PStroker]

I have a autometer boost gauge that reads 15 psi wot with my edge on lvl 5. So i figured i had a boost leak, well i checked and i didnt come up with anything. I set my edge juice to display boost just to see if they were the same and it reads 26 psi wot. Any ideas? oh and my boost gauge is drilled and tapped right into the y manifold. I am going to swap my other boost gauge out of my duramax to see if the gauge is wrong. HELP!?