This is my main racing rig. 4" is the sweet spot as far as I'm concerned on 90% of tracks. The Raceflight stack was a bit tricky to tune at first, mostly because it was pinned. Now that it's dialed in (and unpinned), it really showcases the strengths of the Sinew as a racing frame. It handles brutal gate smacks like a champ, yet feels like a laser beam shooting through the sky. Did I mention it's low drag design also makes it very efficient? My next build will be a mini freestyle rig based on this same frame (except a thicker 5mm baseplate) with a Runcam Split to handle FPV and HD duties. These motors on a 160g quad are just silly!