So that would explain why I have to fill the one that came with it full then lay the other one which is 400# on top of it to get a good surf wave? When I bought them the guy said they were 750# rears and 1100# center out of a Supra Launch so I just took his word for it.. I'm gonna measure the center one too but I'm Pretty sure it is 1100 Its huge compared to my factory one... Thanks Again