Nice modelling.
I like the jet engine idea, but currently it makes the vehicle's front look very spindly. The orky solution would be to instead have _two_ jet engines
If it was a traditional engine then I'd suggest giant exhaust pipes pointing out the sides, but that's maybe a bit silly even for orks for a jet engine (unless it's a hybrid engine with a jet turboboost?).
Not personally a big fan of the side-mounted big shoota - I'd instead put it in a pintle mount on top of the cab for the boyz in the back to fire.
looking forwards to seeing the next ones.