I've got a used #3 stock cylinder and matching piston on the way from Jon, one of the general forum users. I'll pick up a new set of rings from Dean, at Seattle Mopeds. And Benji from Treats is shipping out a 38 tooth rear sprocket.
One of the race rules is that you must use a stock cylinder, but can modify it anyway you'd like. The #3 is what I had on the bike, originally. I broke the exhaust studs, and a couple of fins from my original cylinder, so I've decided to replace it with the same thing. The #3s are nice since they have larger ports. The new rings should ensure solid high compression.
I'm concerned about using the 38 tooth sprocket. Currently the 41 tooth helps get me up to higher speeds, but takes at least a block or two to reach full speed. My concern is that, while the 38 will increase top speed, it'll take me even longer to get up to my potential. And in a racing situation, with only a 1.7 mile drag, it could cause me to fall behind and my top speed not giving me enough to catch up.
The BMX freewheel allows me to pedal up to about 18mph very quickly. I need to tune my clutch springs to engage, conservatively, at about 15mph. I may set the grab even lower for the race and go for an instant grab, even though it puts a lot of stress on the clutch and bell. I'm hoping a stock cylinder will give me more of a low end advantage than the TCCD kit (which is notorious for lack of low-end power). Although I may have better luck tuning the clutch to the Estoril's power band, and having them both kick at the same time, allowing for a noticeable power boost at around 25mph.