Jen, I was kinda trying to say the same thing as Ehoof...I do think the 2 speed has more top end...IF you have a lot of open room to run it...but I spent the money for the Syclone PRO, then spent more money converting it to the 2 needle carb and single speed transmission when I could have saved some money and gotten that in a cheaper car...Here's a link for the Nitro Engine MAIN FORUM...There are a couple good discussion threads on tuning, breaking in, and fuel, so I'll let you browse through all the individual threads to see what you find useful...
http://www.rcuniverse.com/forum/forumid_269/tt.htm