Hi mate, since you are not exactly sure on the 'kind' of smell you need to establish the source first. Take a look at the exhaust manifold gasket since you think the smell might be related to that. The gasket might require a replacement. You can also check the space between the the exhaust pipe and the manifold. There might be a leak there. That leak might cause a smell. Hope you are following.
Oh and once a smoke smell was caused by the valve stern seals located on the exhaust system in my car, they were not functioning properly.