Boost porting cylinders has been proven to increase flow up to 20%. This method has decades of race proven performance and testing. I based the cylinder mods on Dick Teals drawing/specs, as well as the Ackerman 24hp 820 article.
The two boost ports have been taken all the way down into the bottom of the cylinder and into the lower crankcase area. Doing this means that the boost ports act like two additional transfer ports... in the same vein as the 580v5 engines added two transfer ports. Rather than 5 porting, like the 580, I've 8 Ported the 820. Also the "Boost Ports" being all the way to the bottom of the cylinder means that the piston doesn't need to be drilled for boost ports, and made off-ballanced. Your factory piston can drop right in, and you can still benifit from the boost ports. Why pay for mods you don't need was my thoughts?
Two of the transfer ports on each side have been "Siamese'd" in order to increase flow and performance, but the shape of the ports' outer edges have not been change. The rounded sides will help to ensure that the flow of fuel and air remains directional.