Just ordered the fiberglass cowl. The 2500 mah packs I use, do not weight much more than a 600-700 mah pack and they are the same size. I get thepacks from a place on ebay called battery oais. They sell 2 4.8v 2500 mah NimH with your choice of plugs for 14.00 and 3.00 to ship. If you go to my clubs site their is a link to the ebay store (www.coastalplanesrcclub.com). Everyone in the clubs uses these packs and know one has every had a problem. Also my reciver weighs in at 9grams. Is weight an issue with this plane? I was also planning on using a 8oz tank. I know I will have plenty of power, using a GMS .32 same output of an OS .32 but weights 2oz less. Thanks for the input