KYB's are exactly what they are sold as, cheap gas shocks! Lot's of compression and very poor rebound. They will make the car ride more firm since they add spring rate with their compression rate.
For $25 each, the KYB's are a decent cheap gas shock. Bilsteins are a MUCH better shock and they should be at 3 times the price. At least Bilsteins have good rebound control.
This happens to be one of those instances in life where you really do get what you pay for. Buy the Bilsteins if your wallet can stand the price.