That's a hard question. If someone said they'd shrink 4-8%, would that mean anything to you? I've never washed jeans in total hot water before or dried them for fear of affecting the wash you pay a pretty penny for in the first place. I'm curious as to where you want them to shrink - in the ass, length, waist size, all the above? Not that you can control it, but I would think by doing what you're doing, the waist will not shrink one full size down (i.e. 32 to a 31) - somewhere in between. The legs/ass will most likely get noticeably tighter, but will stretch out (although not to its original size) after a few wears. The length will shrink permanently, I'd say 1/2 inch - 1 inch. This is based on general experience, common sense, and conjecture. Were you stuck buying a pair of Zaf's in a size you normally don't get, or do you like the overall style, but just want them tighter in a size you normally wear? FYI - you might want to post this in the denim/streetwear forum.