I recently got the hallman pro rx mbc.. set my boost to 23psi.. tested it on 3rd, 4th and 5th gear, properly holds at 23..

but on 6th gear on high speeds, like 200kph..
the boost slowly goes upto 26psi, and triggers my gauge warning (set at 26psi)
if i turn the boost down.. the other gears go lower than 23psi..

help?

 

Probably cause the load differences. You probably shouldnt even do wot in 6th.
Only way around it would be to go ecu boost control and that way you adjust boost by gear

 

that would be using an ebc and im using an mbc

 

Correct