Usually it will give you less grip but it will make the buggy more stable on a smooth track. If your track is rough the buggy will bounce more because you get faster rebound and if you raise the shock oil to slow the rebound then you bounce because you have to much dampening. So if you race on a smooth track then go for the stiffer springs and higher shock oil... if your track is rough then stay with medium or soft springs. Normally softer suspension will give you more grip (more weight transfer to plant the tires that matter most in the corner) but a harder suspension will make the buggy more stable and react faster on a smooth track. It really depends on the balance between front a rear grip... if you have a lot of front grip you'll oversteer and if you have a lot of rear grip you'll understeer.

If your looking for more steering then here are some front end changes you should try. Get less caster, move the linkage on your ackerman to the back hole, more toe out in the front, a roll center that will keep the wheel more upright when the suspension is compressed, a slightly softer front suspension, or a lighter front diff oil (the diff oil will take away some on throttle steering but give you better initial turn in).