First post (long time lurker):
This was the first thing I did to my Race 3 when I got it a few months ago. It took me a long time to figure out which leds to use. The size is critical. I remember the 5050 (5.0mmx5.0mm leds are too big.
The ones for this board are closer to 3x3. I'll find out and update. UPDATE: the 3528 is the right size. The DigeyKey link looks like the ones I bought. 2 points: 1) the reverse mount is important unless you want them to face down. 2) having flat leads is important. I bought the same thing except the leads were wrapped around the edge of the led. I destroyed all of my fingernails bending the leads out by hand and then flattening them with a hemostat. BTW - 100 of the ones I bought cost under $7 shipped to the USA. Let me know if you want the eBay link.
If you like RGB Leds, and you can solder, then this is a worthwhile mod for this board. This and the program-ability are the reasons I bought the Race 3.
https://imgur.com/yG6DrFWAlso, The programming is already in the firmware on this board and is the same as for the Pok3r RGB. There are some good Youtube videos describing the color options and lighting patterns.