Sonic's Speed[]
Sonic Unleashed shows that the Light Speed Dash clocks in at 390 SPD in the checkpoint speedometer. Sonic moving at his fastest within Unleashed clocks in at 3519 SPD. Let's do some simple math, and I mean incredibly simple. I don't think this even needs to be evaluated.
3519/390= 9.0230769230769
9.02x FTL. Less than a 1.11x gap for FTL+.