General Grievous Speeder Bike

I wanted to make a Speederbike, and for who else to make one than the awesome General Grievous? Darth Vader, but hes not really the speeder type, so lets stick to Grievous. instead of working around a nice outside, i started with a functional inside, based on the famliar brown Republic Speeder and added the outside later. the original sketch didnt work out in this model…

anyway, here it is
the gallery:

as you can see in the gallery, it features a tank(lid), storage and, for mr. four-arms himself, the guns are operated separately.

any hints, tips or general criticism?
(the design of an actual repulsorlift engine would allso help…)