I am in the process of redoing my upper intake manifold (plenum) because I had a vacuum leak on the backside. I have a question regarding the use of RTV when putting the upper intake back on. The gasket used is not your typical flat "cardboard" type of gasket. It's a plastic tubelike piece that fits into a groove all the way around the perimeter of the upper intake. The repair manual makes no mention of using RTV to further enhance this seal. I was unsure whether, due to the type of gasket used in this application, RTV is a good idea to use here or not. Any advice is appreciated.