CUSCO Strut Bar installed on my RAV4 Prime 

Hello John. No. I have not notice any difference in the handling of the car.

not even aggressively, I've noticed acceptable handling when turning slowly. D to C grade handling after installing mine

Hello Nick. To be honest, No. I feel no difference in the handling of the car. It did come with some basic instructions. But nothing seems to go in those other holes. At least not in the Prime.

I just did this install on my 2021 R4P XSE. Yes, there are two additional bolts which go into those two other holes. Cusco provides the bolts and the nuts (with clever handles welded to the nuts so you can get them into position.) Just don't over torqued those other two bolts beyond about 25 ft-lbs, as the heads will twist off. Don't ask my how I know 🙂 Also, you can take a hacksaw and cut away part of that bracket which was removed, so it will now fit along side the strut bar and hold up the A/C tube bracket.