Thanks for the replies.

We've tried to get the boost lower but we haven't achieved that. It's a Garrett -31 actuator and we have lenghtend the rod as long as possible to get the boost down without the being too lose so the wastgate has no preload.

The chip is made by Dutch Cosworth specialist Gerry Knubben. Some people in the UK also know this guy. He did some work for Ford Motorsport in the 90s