no boost gauge is slightly off im going by the read out on the DD tellin me the boost is going to 11 then dropping off to 9

standard boost is around 7-8psi, so 11 psi is over standard.....very conservative though thats for sure
 
could be a shitty map ? either eay that not alot of boost so im jus going by what iv been told he told me 17 ish psi should easily see 240 bhp ?i do need a new air flow metre as it has a part of it broken aswell so that will help my problems ?