For a 2010 Dodge Challenger r/t classic 5.7L with a 6 sp. Manual transmission do I need to run 91 Octane fuel? Dealership is saying I only need 87 but i found online and in an owners manual to use 91 since its the 6 sp manual. The source I found online said the same thing but it also had a disclaimer that said it excluded the rt classic model. Any suggestions?