Sam, sorry not got your email address at work. The restrictors as John Stevenson pioneered can be made out of screw threads drilled to size - might be worth a try if you are deparate. I have nothing spare that would suit you just now, however I found the needle valve option quite good although the location on the Evo and the length of tubing you would need are a PITA (pipemore in Glentrothes do them - there was an earlier thread in drivetrain). Sometimes I like to have the valve as you can then adjust the boost without getting the laptop out and changing the duty cycles. JECS can be a bit of a nightmare to get right, I expect GEMS is a bit cleverer with PID control and gets to targets better? 0.8 to 1.0 to 1.2 are quite big jumps and I usually find the 0.1 mm increment makes a massive - eg 3 PSI difference.

If in any doubt I use a small restrictor - the STis I think use 0.8 and end up with only about 50% duty cycles - at least you can get high enough then with your map and the 0.4% granularity in the duty cycle seems enough to get what you want.

I am finding I am just ending up living with 1-2 PSI lower boost in hot weather. Also with the Motul oil it takes more of a trash (perhaps I am imagining) to get the turbo really hot, and an 18 PSI on a commute can soon turn into 21 on a thrash. I hate boost control!

Hope this helps - are you on the track on Sat? Sadly my IHI hybrid will not be on by then, but at least it is another change for me to learn to drive