It depends on the type of installation you need. If you're installing a new gasket, for example, you'll definitely want an expert to do it. If you're just putting in new spark plugs, though, you can probably handle it yourself. It really depends on the project. That said, it's always a good idea to get professional help if you're not sure what you're doing. Mistakes can be costly and dangerous, so it's always better to be safe than sorry. If you're not sure whether or not you should hire an expert, consult with someone who knows what they're doing. They'll be able to give you some good advice and point you in the right direction.