Yes, in will make it leaner. High speed needle affects the whole range of running, so high speed needle must be adjusted first, then low speed needle. Which ever servo is twitching, try setting you trim to the middle of the range, and then take the screw out of the servo (the one that holds the arm to the servo) and place it back on with no load on it. Pull the arm off, then set trim so it does not twitch, then replace arm and center screw. There is a link to a new CEN sponsored website in one of the recent post. I've had better luck getting answers on there. Try giving them a call. Very friendly and responsive. Plus you've got their undivided attention. Hope this helps.