Zman39

The prop is wrong. You must run APC speed 400 or pylon props turning the rpms.
You will most likely have to run a APC 4.75x4.75 or 4.75X4.50 due to the high kv of the motor. The 6x4e is a thin prop designed for MUCH slower kv motors. I'm guessing that due to the flex of the thin prop you did not over amp system.

That said you can expect blistering performance with the above props. You MUST balance these props...if you don't you run the risk of damage to the motor bearings.
You will be in the 110 to 120 speed range with the new props. You may try a APC 5.0x5.0 but check the amp draw on the smallest prop then work up to close to max amps. Make sure you check ESC amp range 60 amp min. and max amp on motor per mfg. Your amps will drop in the air. Amp test are static on the ground. I'll guess your pushing past 60 amps.

buy 2-3 of each.

Rule of thumb...The prop is the transmission of the plane. That's why there are so many lengths and pitches on the market.

A diff. mfg. will yeild a diff. result as most mfgs. do not use the same air foil design on the prop. blades.

Post you results....start small and work up. you won't believe the diff. in the correct prop...watch for torque roll to the left on launch.
Cp