The Supplement section is in Supplement section 11 (11.4 - Special Take off and landing operations). It has a very an identical set of limitations to the Limitations section at the beginning but the performance graphs are more restrictive for MTOW and typically give about 2100kg at sea level ISA day. The retrofit kit s a fire extinguishing system (I think) and mentions a ram air ventilation system. I can E Mail you the relevant bit if you want.