if you have a 92-95 or 96-00 civic, they'll bolt in with the proper mounts. no need to extend anything. you can also retain your stock radiator. many people go for the dual core del sol or aftermarket if they change them. the only thing you need to shorten or extend is the catylitic convertor to the exhaust pipe as it may be too short or too long depending on what setup you go with. other than that, the B series will bolt into your car.