Definitely my most challenging build yet. Originally the frame came with 15mm of build space. I cut down some 20mm standoffs to 17mm to give myself some extra space. There were some features I wanted that just wouldn't fit in 15mm. Literally, there is only enough space left inside for a little air flow. Otherwise, awesomeness!!! Quick, balanced, and most importantly loads of fun. The 300mah is a decent match, I may try something a little higher to see if there is much difference. I tried a bunch of 260mah's but they are on the cusp of being underpowered...too much sag. Just got in a Racer Nano to try, looking at the Predator Nano also. The one thing that I'm not too sure about, is the screw holes on the guppy frame are countersunk. The problem being countersunk holes on 2mm and 1.5mm CF doesn't leave much material for structural support. Time will tell.