With a bumpy track you should be using a light shock oil. Sense the hyper 7 piston holes are pretty small I'd start with 40f-35r or even 35-30. Also use medium springs.

The bumpier the track the softer your oil and springs need to be to help that tire mold to the track surface easily. If you have a heavy weight oil you'll just bounce because the suspension doesn't soak up the bumps like it should.

The smoother the track the thicker the oil and springs should be. This really makes the buggy feel more stable and consistant but if you hit a bump it will screw you up pretty bad. A lighter oil will make the cornering feel kinda sloppy on a smooth track.