Are you lookin at doing a Rocky or a Feroza? IMO, they are both capable units but I believe the Rocky is the only one of the 2 which has a diesel engine whilst the Feroza comes with a 1.5 or 1.6 petrol? 5K should allow for some decent mods to suspension and engine on either. To convert a diesel to gas means you have to have the two tanks on it and running at the same time as diesel gas conversions work hand in hand, at the same time and not one or the other. Might be a substantial amount of weight to add and fairly costly even with the rebate. You can still do things on both like; exhaust/extractors, UniFilter or K&N filter and a few other things but you'll need to do some research on this as I'm not totally familiar with the Daihatsus to help out too much. Good luck.