If all goes well this week that thing should be mine this weekend! Hopefully nobody beats me to it!
What is the stock gearing for a RC51? And what brand sprockets are yours?
Stock gearing is 16/40, way too high.
Drop it to a 15/41 or 42. Much nicer.
I use a Renthal 15T front and Vortex F5 41T rear (special sprocket due to Marchesini wheels) with an RK 530 X-ring chain.
For stock rear wheel, a Stealth sprocket is both light and long wearing.