Flame suit on: I have multiple ST 40's, 45's, 51's and three 90's. One has a Nitro Pipe (unmuffled) on it. Each has been run on everything from 5% to 30% and each and every one performed flawlessly on ALL of the different amounts of Nitro. I won't go into settings, prop sizes, glow plug selection or any other specifics but I will say that properly tuned the G90 WILL run absolutely GREAT on 15%. Does it need it? Depends on what you are trying to accomplish. That's my two cents.