The title explains it, if its possible how do i achieve 6"s of suspension lift on my 99 isuzu rodeo? The easiest way would be 3" suspension and 3" body lift but that isnt a true 6" suspension lift. So whats the advice?
Re index the torsion bars and crank it up 6 inches. Ride quality is gong to be awful. You will need to to flip your balljoints. I would also recommend getting calmini control arms if you want to go that high. Don't get longer front end shocks or you will destroy your rack and pinion. A diff drop will be necessary also. For the rear get ome or calmini springs with some spacers. You may also want to look into some bent upper links from Calmini for the rear end.
It would look sweet but i'd never lift my Rodeo up to 6" with just the suspension (unless I got an IFS drop lift kit, but that probably isn't going to happen), but the ride would be horrible, and you would probably have absolutely no downtravel left. My Rodeo is right at 3.5" of lift with just the suspension and it's the highest i'm going to go with it, it rides really nice and it's just high enough where I have to hop into it, so I don't really want to go any higher.
I don't know if you can even achieve 6" by cranking the torsion bars...even if you could it wouldn't be drivable. The only way I know of is to buy one of those kits from Indonesia...one guy around here has done it, somewhere in Readers Rides. A more common (and much cheaper) approach is 3" suspension and 3" body lift.