Quote "the pegasus ex works comes in at 85 to 90 kg a lot of people are getting readings over 100kg,"
If the ex works noseweight is over 100kg, then there is something very wrong, and as the upper limit for the coupling is 100kg there is no room for additions at all, such as gas cylinders.
Even at 85 to 90kg it still is questionable as to whether it is sensible, given that the only place gas can be carried is in the gas locker, adding more than 15kg to the noseweight before loading.