Depends what kind of driving you want to do. Auto-x? Road course? Rally? High-speed? Low-speed?
And define understeer? Is it at low speeds or high speeds?
Reason I ask is because you can setup your car to have a twitchy rear-end for auto-x which is great to get the car rotated but once you bring it to the road course at high speed that same setup might be dangerous. For example snap oversteer if you can't handle the car.
Even small changes such as a 0.5" difference in ride height in the back can make a big difference.