I did the stupid thing of paying just over 100$ for botch platnium 4s and they were the biggest waist of cash!! with about 300kms on them and they started to fall apart already and made my car run like crap. I then put in ngk g power tr55gp. They were fairly cheap so if they didnt work good id just go back stock but theyre doing good and i noticed a slight slight gain in power especially over 3gs.