>Â*I have read that the installation of a ''hop up'' kit will increase the top speed to approx. 90 km/hr, is this true?Â*
I don't see how the hop up kit would do anything except make it slower. If your talking about the full hop up kit that adds the front and rear aluminum arms, you'd only be making it heavier. It does nothing to the engine or gearing so if anything, performance should be slightly less than stock. It would probably be a marginal loss, maybe even hard to tell, but very doubtfull that it would increase speed.
Also, your very lucky to have a Redcat stocking shop locally. Many of us have to acquire parts on the Internet. Because of this I've built up quite a supply of backup parts, but unfortunately, half the times you still wind up needing the part you don't have on hand. A local dealer would make things a lot easier.