Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
Do you mean knocking as in rattling exhaust noises, or knocking as in cylinder detonation?
If its detonation, and it didnt do it before you put on the filter, then the obvious answer is that the air/fuel ratio is too lean and it needs richening up. You should try and get the chip reprogrammed to deal with this.