I'm on FB mate and loads of pics on there. I'm friends with all the Thundercat racers, I use to race.
Other than the Flywheel and exhaust which both make a huge difference that you can both feel and hear. The engine now revs like a motorbike thanks to the lightened flywheel.
No other single thing on its own has made a noticeable difference, ( bit like running 99 octane fuel over 95, or leaning out the 2 stroke oil or adding octane booster) however I have found that the 10 or so small improvements I've done when all added together have made a difference. Nothing drastic, but if your racing it's the difference between winning and losing.
All my props were over pitched, loosing weight (mainly from the hubs) seems to equal 1 degree of pitch and the various other engine and exhaust work is improving power and gaining me revs. So instead of having to buy new props, I have made use of the old ones and gained some speed and acceleration.
I have just finished lightening a Ron a Hill eagle 3 prop, I've managed to trim off a touch over 20grams and blended the square edges on this over the hub exhaust prop. It's not going to make a drastic difference, however I have extensive records for this prop on the current setup. So any gains/loses will be easily found!!!