did a bit of mapping on a car the other day on GEMS, because owner/friend complained of "boost surging". Basically at full boost, the boost 'hunts' up and down between about 1.7 and 1.2 bar. The only way I seem to be able to stop this is by turning the boost right down in software so it's just running wastegate boost. Anyone experienced this or have any ideas? It's a Perrnin 3 port solenoid with Turbo Technics turbo (supposed to be 400bhp capable). Seems almost like hysteresis, w/g opens, boost drops, w/g closes boost rises. I initially has the bosst map quite aggressive with 0 (pressure vented, no pressure to actuator) up to the desired boost, then 100% duty (boost to actuator) once desired boost reached. I've tried ramping it in more gently (30, 50, 85%) but it only really results in slightly lower boost with and doesn't completely get rid of the surging. Ideas please...