You can get a nylon adapter(see http://www.usplastic.com/catalog/item.aspx?itemid=23282) that you can jam or glue into a 2L bottle neck (that you have chopped off the bottle) to make a 2L bottle threaded male - to tubing adapter. I'm assuming you want to have a couple feet of tubing to increase the head pressure on the filter and make it filter water faster.
Sawyer has emailed me that the old SP 122 and the new SP 132 filters are internally the same-with same guarentee. I am about to purchase one of them, and I like the idea of squeezing the water source bag to filter quickly when needed. Does anyone have any experience with the SP 122 as far as having a closed water source bag and applying pressure to the bag to filter faster? Or will a squeeze filter system work only if the bag is directly connected to the filter and the connection is large diameter like a 2L bottle (like the SP 132 system)? Thanks.