Have you recently checked that out?, do any mods change that less or more? plus your weight on it, can that be relevant to riding it?

 

I actually weighed mine once on scales at work and if I remember correctly it was just about 750lbs (with me on it). So that would make sense with the bike (wet) being just about 535lbs. Dry weight is listed at 518lbs for this bike, I believe.
You can lighten it a bit without the stock exhaust, but other than that I don't think there is anything major you can do to lighten it up.

I think the biggest difference is rider weight. A buddy of mine has the same bike, but he is like 5'6" and only weighs 130lbs.
I'm just over 6'2" and weigh about 215lbs.

Noticeable difference in performance between the two of us.

 

260 kg with full fueltank and Scorpion single can slipon.

 

I think the main reason these bikes are so heavy is the steel frame and the long wheelbase (more material), but mainly the frame.

 

And that if you don't add any chrome rims too...lol.

 

Also the engine is bloody heavy as well.

 

Stable as hell, though!