Mikey... two of us running 6.5's today
one on a SP equivalent V2.1 speedo and the other on a SXX v2 both with zero timing on the speedo and zero timing on the motor...
One had 21/84 FDR of 9.75 (v2.1)
Other had 22/80 FDR of 8.86 (sxx v2)
Mix of Astro and Grass at Oswestry track, Air Temp about 28c
Both motors were temping around 145c
Neither thermalled
Not sure if that helps...
What pulleys are you running? so i can calc your FDR ?