Its very hard to actually find info on them. When I did research on them it took me the longest time to find anything. Unfortunately, I lost alot of the links to that info when my computer crashed.
Here is one link I found, Garrick Demeyer use to have a really good page on them, but he is in the mist of redesigning his site.
http://www.constrictors.com/Collecti...tedPython.html
For the most part, they grow to 6 - 7 feet. Females have the capability of growing to 8 feet. When I was doing research I ran into alot of disputes about their size, for the most part they seemed to be confusing them with dwarfs, and with SD x Dwarfs. And some even made accounts that couldn't be right since SD retics weren't in the US for that long. Along with that some were even feeding them too much causing them to grow larger(8 feet), and thus adding to the dispute.
There was this web page I found, where I believe Steve Gooch did a feeding experiment on them, it was pretty imformative about how they can grow larger if being fed too much, and how the mainland, dwarf and SD retics had anatomical differences, (in the face and snout.) Which further concluded that they were actual subspecies, and were not selectively bred to be small, which at the time I am guessing was a controversy?
My best advice is to just keep researching, all the good info on them is actually pretty hard to find, I did about 6 months worth of it before I decided to get mine.
Hope this helps