E-racer. Try to get ahold of 2 20oz bottles and see if they will work. Or you could get some body to measure the diameter of a 1lb and a 20oz bottle. I think they are the same diameter just the 20 oz is longer. It looks like the 2 1lb bottles is about as big a diameter as you can fit. You might have to do some more plastic cutting, but I think it will work. I had 1 20oz bottle in my 03 1000. I never got another bottle to try it, but I think it will work. I know running a big shot (50hp or so) a extra 1/2lb would really help.
2 20oz bottles = 2 1/2 lbs.