Boards are designed to flex within certain rider weight ranges. This is what allows them to flex into, and out of, turns. If you are too light for a board, you will have a very time making use of the boards camber. This will translate into the person not being able to make the board carve. If you are two heavy for a board, the deck will not "pop" back out turns, and it will feel very "noodly." (I'm sure Snowolf can explain this much better than I can).
Almost every board mfg will list the suggested weight ranges for given board on their web site. I just looked at the Burton site. You are way over the weight range for a Custom 156. Here are the specs:
156: 57-80kg (120-170lbs)
162: 64-86kg (140-190lbs)
166: 73-96kg (160-210lbs)
Your not just over the suggested weight limit for the 156, you are way over it. There is also the consideration of boot size. The 156, accroding to the Burton site, will fit up to a size 10 boot. If your at an 11, you need a wider board. The 162/166 will fit an 11 size boot.
IMHO, there is no question you should get another board. That thing will prolly ride like mush to you. One thing to note, however, is that the various different manufactures have radically different weight ranges for the same size board. For instance, the K2 WWW (a pure freestyle board) claims someone who is 200lbs (94kg?) can ride the WWW 152cm board! The point, is do your research before you buy, and don't assume you have to ride a longer, or a shorter, sized board.
Hope this helps, and feel free to ask anything else.
"Nancy Ninja Nabs Nefarious Nymph. Pays Price Per Pissed Pants!" -Flick
"Up, up, my people, let smoke and flame be our sign!"
-The White Rose Society
Last edited by sedition; 05-14-2008 at 09:25 AM.