What you're seeing is exactly my point of an optimized setup. Sounds like it's time for you to make a jump in either turbine wheel or housing. More than likely wheel. That will have a much more significant difference than a housing AR change.
And I will say it again, keeping that 1:1 PR between intake and exhaust is crucial in making big turbo power.
I'm pretty sure you are right about that. I'm still amazed it can make almost 700hp thru a single .96 A/R T4 housing/wheel with a full 3" single exhaust. I've been hesitant to change it simply because it's so very responsive on the street. There's no waiting for boost - ever. You hit the throttle and you're busy steering! LOL
