I bought a Bud head some time ago, but I don't know which dome does what really. I would like to know more about the chamber shape and how it changes the performance of the engine. It's for my 03 125SX and I have provided pics so hopefully someone can educate me on the finer points.
I also have an FMF Shorty silencer that I use on this bike, I like midrange torque.
The last pic is the stock head for reference.

http://img141.imageshack.us/img141/...rtbikehead3.jpg

http://img189.imageshack.us/img189/...rtbikehead2.jpg

http://img813.imageshack.us/img813/...rtbikehead1.jpg

http://img207.imageshack.us/img207/...rtbikehead4.jpg

my understanding in head shape design is very vague but, i still believe that is more of a black art, based more on experience than on calculations. however most tuners find maximum squish velocity (MSV) to do head mods.
squish is a well understand process that consists in the turbulence generated by the approximation of the piston to the head on the upward movement of compression.
compression ratio is of course very important and those two factors are connected. generally the more compression ratio the higher have to be the MSV.
MSV most important factors are head to piston clearance and the squish area, the area on the outer surface of the chamber.

another critical design parameter is surface area, as well plug location. mass of head is important to equalize temperatures.

and, to me ends here

Does anyone else know about these heads? I want to get this put together soon and would like to use the low/mid dome...which one? Help!

Just try them both. Probably faster than trying to type a theoretical answer. You know you are going to compare them anyway.