Cut off the old 'towers' and twist the lower (or both) beams to increase the ride height, this is best done if you are running extended trailing arms, re-construct the towers to accept longer shockers, remember that when running longer shockers and racing off road, the towers MUST be webbed as the damping force of the shockers is also transferred to the tower and they do break off.
Good quality shock absorbers are a good idea to use on your vehical, cheep ones from the local "K-MART" will possibly 'fade' or lose their damping efficiency as the race progresses, Stock VW shockers also 'fade'.
The rear end of a buggy needs quite a bit of work done because its the business end, dropping 6-8 feet after a jump, it may look smooth on landing but with a rear engined buggy, you have the weight of the motor over-hanging the rear wheels, so most of its weight, IS carried by the rear end, so bigger the motor, the more weight that the suspension has to cope with, so it is not unusual to have multiple shocker setup either side on the rear end, I run 1 OME-007 and one Bilstein 'coil-over' that is specially made for off road use, these 'billies' are worth from $AUS300 up, thats without the coil-over, that is usally extra.
If your in the USA and you think that the prices that are advertised here are high, I already know that most stuff in the US is extreamly cheap,
then the price is upped with the exchange rate then import duty ontop of all of that.