I reviewed both your map Tony and Lee's, they both hit the same injector duty (and the limit) at the same points. It's certainly injector duty related but since it is happening as low as 3500rpm it should not be because they are at 100% duty. They are infact at about 60% in each case at 3500rpm. They were aproaching 100% as RPM rose though, so still the injectors are too small as we know but my point is that they should not be hitting a wall at 3500rpm. I've been trying to think of common factors between your 2 engines. Dave's was not an issue at that boost level since his 440cc injectors ment we didn't need as much duty.
I'm going to check with Adaptronic on the off chance there is a bug in the 6-cylinder code that means the injectors hit a premature limit. I know for sure that this odd-limit has not happened in any of the 4 cylinder engines I have mapped. I'll keep you updated

Chris