You may either want to swap the elastomers or exchange with the short travel version. Sounds like you obviously hate the bouncy effect and just want simple dampening. If that's the case, then the ST version is probably your best bet. Suspension seatposts are only good at providing dampening while seated and pedaling on rough terrain so if you've got your bum on the saddle during a "landing" you've got it all wrong. I'm assuming the Mamba is a HT. Ride it like a HT and not like a FS.

VD - yes, Thudbuster suspension seatposts are still being produced. By Cane Creek and MRP also does the similar Tamer sus seatposts.