Minecart Boosters not Working

[RyanBarnard]

We have built a series of minecart boosters in our SMP server running hMod 135.1 with Minecraft Server 1.3 using the technique shown in this Youtube video:
http://www.youtube.com/watch?v=gPls6LXlkGI

It works great in vanilla Minecraft, but now in hMod the boosters just don't give the carts the forward momentum to push them as far as they used to go.

Thanks!