Cart Speed

Hi guys,
i`m looking for a plugin which lets me speed up a minecart more than the normal full speed.
Either setting the full speed for all minecarts up to a configuratable level or speed up a cart by placing a specific block under a booster rail. In second case it would be great to specify the block and speed in a confog file.
Is there someone here who could code this or does something like this exist?
Thanks,
Kadaverschreck