[davebslater(uk)]

If you can get at the overboost cutout located under the dash , you can run whatever boost you want . Some guys in america are running 14 -16 psi on an otherwise stock engine , with a turbo and air fuel ratio meter to monitor if the engine is leaning out under boost . 12 psi would be achievable with a manual boost controller , std is 7.5 or 9 psi , double check if yours is low pressure turbo , the compression is higher to compensate , hence limiting the amount of boost . The keywords here are detonation , avoid at all costs , engine damage and destruction result . You should be safe at 12 psi although no guarantees could be given because i dont know how good your engine is !! . hang around on the turbobricks forum , you can pick up loads - exactly why i developed the boost controller - its the english version of a dawes device or grainger valve .