there is a boost cut out in the ecu's at 1 bar. You will need to chip it if you want to go past that point......I believe stu does a chip for these Not much point running past 13psi with these anyway because of the turbo's, fitting a T28 is the way forward !

Klinger headgaskets are also a good idea but then again I never blew a standard one when I was running 15psi for a couple of years.

Duncan