The Plus 8 I have has exactly the same chassis as the Aero S3, S4 and Super Sports. So no roll bars, inboard front coil over suspension, fully floating rear coil over suspension. It is all rose jointed, so I suspect a level of adjustability.
Later Plus 8s produced after the S5 was announced have the S5 chassis.
Could you let me know who did your set up? I'd like to talk to them!