GTST, the only classic model rexes that were 1300 kg were the wagons, 99-00 sedans were 1270, 97-98 were closer to 1230.
My 2000 model ran 13.7 stock, so they are pretty capable. But yeah, some people don't know how to drive too.
And to all you guys, 13 pound is stock boost in a rex. They are a lower compression motor and can handle more boost, but at the cost of more lag.