I've never replaced an ignition coil boot. It's cheap, about $12 for 4. Rockauto was selling them so I thought I'd just buy them to see if I can replace them while also replacing my spark plugs. The ignition coil boot on the 2015 Mazda3 isport doesn't seem to be able to be pulled off or twist off like on the tutorials I've seen on YouTube for other car make and model. Maybe it simply doesn't come off for my car?