If you are driving the speakers too hard, new wires won't help. What will help is not driving the speakers so hard or putting in speakers than can take what you are doing.
The idea that large diameter wires are needed for short speaker leads in a car is simply wrong. 100 watts peak power across 4 ohms is only 5 amps; no need for "monster cables" there.
(Altho if your wires have been wet and you have corrosion in the terminals at either end - then sure, replace THOSE wires.)

MarK Christopher
Systems Solution Engineer
EF Johnson Division
JVCKenwood USA
Irving, Tx