Clever - I didn't think of that.
Think mine was 300kg front and 550kg rear on the IVA, with a not small inspector sitting in side it.
I'd be surprised if it was that much, from recent activities, the hubs inc disc and caliper / drum and arms are about 20KG a corner, 998 about 120KG so say with tyres etc you'd be up to 250-300KG in running gear, 350-400 by the time you add the frame then depending on what you have done with "the other shite" like panels, lights, seats you could be up to 5-570 i'd say.
I'm thinking the other way now, and apart from adding miles of CDS at enormous expense, my new 998 is 75kg, replacing steel with ally panels, replacing heaving quality mirroes and lights with cheap shit plastic, using a alloy fuel tank etc etc, i'm hoping i can get below 400kg
IIRC, if you can get below 400KG you can get a "quad" IVA, which again, IIRC is less strict than a passenger vehicle one