This plugin work perfectly for VIPS, if you want to earn more money in your server, you can sell this option. The users that have especificated permissions will have x2 capacity in her enderchest.
Commands: /ecp --> Will show you all help.
Permissions: EnderChestPlus.use
*In the config, you will have access to modify the slots and other things.

EnderChestPlus 2015-07-31
Enderchest with more capacity for VIPS