Almost everyone went to a cascade purchase because there is less friction. Cascade in this case is a 4:1 pulling on a 2:1 for 8:1 total ratio.
The typical rig is with your downhaul lines out to each side coming in from the downhaul adjustment mast cleats and turning blocks, up to a single block with becket (just hanging in space right now), down to the big block at the bottom of the mast, back up to another single hanging in space, and down and out via the turning block/cleat on the other side of the mast. If you count, that's 4 up/down; there's your 4:1. On the two single blocks, you put a line on each becket, and run those through the blocks hanging off the sail, one each side, then down to the added cleats on the side of the mast. That's your 2:1. When setting up, pop the downhaul adjustment lines, and pull those single lines as tight as possible when cleating (the blocks will pretty much hit each other). That will give you the right adjustment range for the downhaul. The big block at the bottom= less friction and spaces the lines out around the boom. I'll look for a picture somewhere. The stock system works, but depends on the small rollers on the bottom of the mast (not exactly high quality blocks).