I forgot the main sheet. My M15 came with 27 feet, 3/8 inch. I really don't know if Montgomery supplies or specs these out, or if it's all dealer prep. Anyway, there's no magic number, save for the minimum, which is quite easy to sort out, if you just trace the path that the line has to take, with a little extra when everything's run out as far as it needs to at maximum. ************** Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut000500000000... )