Those chambers usually come in at 75CC range or less I am sure as an aftermarket maker they have to decide--will these heads work with all the pistons and combos out there already--I think that is the consideration--OK you get the small chamber and now everyone will start needing dish pistons for the street stroker combos--it will be a challenge of sorts to get correct CR for street--Do you really think that chamber is going to add anything more than a tenth or so? It sure won't be a five car length deal in most cases now will it? The Sidewinders are an EASY to use head that is high quality and cheap--better quality by FAR than the previous low price leader--I say again--BY FAR! It works super easy with shelf stock ( read less expensive) pistons and is like an Edelbrock in terms of power making ability ( if not better) so I love them. If I want a race head well..I can deal with Indy--wait....I would rather go slower. BTW just got a set of new SR indys--the deck was cut with three passes using a narrow cutter---now who in the world thinks that is a good idea?-deck had at least a two thou "step" at each of these lines--and the valve job had so much chatter in it--looked like the cutter used was from 2006 so....after spending time and $$ to clean that mess up I am even more convinced that these Sidewinders are good enough for the large percentage of my builds
These heads are a good thing--I could care less about a closed chamber version--that is not what they are aimed at.