I have a 2005 rx1, with an mc express turbo. I currently have the stock track, 151. I have been told that if i want to go with a 162 challenger extreme, i will need a tunnel extension, extroverted drivers with a 3 inch pitch , and some brackets for clearance I assume. If there are any other tracks that would suit mountain riding better, let me know. Also can someone explain what these brackets are that i need and where i can buy it. Any advice would be appreciated as too what the best direction is.