I have a couple of noob questions about fuel injectors. First, is the only way of replacing the fuel injectors to depressurize the system by letting it die? I'm not replacing the fuel rail; just the injectors. The second question is, when I go to place them back into the cylinder head, should they "snap" into place or anything like that? I'm curious because of how the o-ring is suppose to sit. I replaced them eariler today but didn't notice any snap or noticeable securement. Thanks for any info!