What diameter front tire are you using? I find that the car likes a smaller range in the front tire compared to others. I typically run 21.8-22.4 on most of my setups (no shims under front knuckles on GLR), and my setup dropped onto the car from kit for pretty well. If running large diameter tires (over 22.6), I think you will find the nose up in the air.
To lower ride height with larger diameter tires, you will probably need to snip the damper pistons to allow more uptravel on the arms (as described in the build guide). Then reduce preload to find your sprung ride height, and reduce droop to match it.
I'm using the low profile PN KS slick's on the front and Marka V1 R05 in the rear..
They measure 23 right now. I have a tire truer and can turn them down to achieve the smaller diameter.
I'm measuring pretty close to 2.5mm in the front which would make sense then.
I assume you're running the stock setup in the RX28 with the 1.5mm shim on the front knuckle then?