Aftermarket parts are made by someone other than the original equipment manufacturer. In our experience with Toyota vehicles, very few make an aftermarket part that matches O.E. quality. Most independent shops use aftermarket parts extensively as they cost considerably less and offer a better profit margin.. We do occasionally use aftermarket parts with our customer’s approval, radiators and catalytic converters for example, because of the large difference in price. Koyo radiators are very well built, offer a lifetime part warranty and cost considerably less than a Toyota unit. Aftermarket catalytic converters are not even close to Toyota in quality but the price difference can be so great that it makes a good option. In general though, we highly recommend using only Toyota or O.E. parts on your vehicle.