It is quite usual for boost to drop as rpm increases. Sometimes you can increase the wastegate solenoid duty to accommodate for this other times it is because the turbo is unable to provide the volume of air to accommodate the required boost pressure at higher rpm. For me personally I dislike the common boost spike and try to minimise the spike while increasing boost duty with rpm to achieve a flatter torque curve, however lots of people like the exact opposite!

Also, thats a really nice curve. The torque doesn't drop off fast enough for the power to really tail off before the limiter. Any more boost and I suspect all you would gain (with that turbo) would be a larger midrange torque figure which tailed off more rapidly. You have a perfect road spec car imo. Your AFR is also really rock solid.

@nevsrevs - Your AFR is not right. You can see that where you make peek boost your AFR hasn't settled to target, a nice smooth AFR is a sign of a decent tune... or a wrong lambda gauge! I wouldn't say you are running particularly lean as you come on boost however the afr could be a lot smoother. An AFR or 12:1 is fine for that boost, although I might be tempted to go a little richer towards the rev limit.

Cool graphs, thanks for sharing!