just bought a 2008 Tige Zi; the gas jacks on the two compartment covers on each side of the engine had been previously replaced, but with the wrong size jacks. By trial and error I've determined that 17" is a good extended length, and at that angle the jack force needs to be a minimum of 100 lb to just barely keep from falling. I'm thinking of going to 110 lb, but really would like to know the correct size according to Tige. Anybody able to help?