What size 6S are you using? I put a Grayson Monster Jet on mine with a 80A ESC and a 7x6 prop. The fastest I have been able to get up to is about 140MPH (via GPS logger). I run mine with FPV Gear on it. It recently self destructed at RMRC's FPV Fest. I was doing a low full speed pass down the runway and I think air got under the canopy and blew it apart. I am rebuilding it now, but always looking to go faster.
P.S. anyone have a 3D model for a replacement canopy?