When you want the ultimate in suspension bushing performance, you want to install a polyurethane bushing kit. Polyurethane bushings are less susceptible to damage from temperature extremes than regular rubber bushings. They also have less give, and are less likely to squeak than rubber. Polyurethane bushing kits can be purchased anywhere you buy performance automotive parts. Summit Racing Equipment is one of the more popular online retailers that supplies polyurethane bushings for just about any car on the road. Jegs is another very popular online source of high performance upgrade parts, including polyurethane bushings.