Are any of you guys scared to do these spark plugs? Had a customer a while back that needed timing chains, I declined due to the mileage and a lot of times they are neglected and need an engine anyway. He had a local shop do it, but they wouldn't put spark plugs in it. He called me because he had a misfire a month or so after the timing chain job, had a bad coil so I put plugs and coils in it.