My Magnum .15 requires a YS 20/20 fuel (20% Nitro 20% Oil) to get a contest inspected 17,300 rpm on the ground. 30% heli fuel let's it tach around 17,800 rpm, just a hair over. The main thing in SSC is making sure that engine runs the same the entire round.... that's where your sucess lies, but you need to be as close to 17.5 as possible at launch. Go up to 10% and see what happens.

Regards,
GPB