You are correct, if the exhaust comes with it's own gaskey, it is better to use it. The head only needs seal if the rings are missing, some people dab a little around the outside of the ring, but that is just a choice, I've done this on my savage and seems to work pretty good. As far as his savage, I would recommend sealing the new engine, mine leaked two years ago when I purchased it. Here is a picture of my savage. And a picture of my Traxxas Jeep that I also sealed.