Modify at your own risk!
Increased Forward Flex
If there's one mod you should do right away to your TLT6s, it's flipping and filing the forward lean plate. Flipping the plate will give you a bit more forward lean when in ride mode, mimicking highback support. Filing the hole upwards will increase the amount of forward flex, and will allow you to bend and move a little without telling the board you want to turn. See here for an excellent splitboard.com forum post by Phantom's Design Consultant, Barrows Worm de Geldern, on modifying the forward lean plate for increased forward flex.
Increased Lateral Flex
Cutting slots next to the pivot point of the lower shell has been found to increase the boot’s flex in the lateral (side to side) direction. All slots should terminate with a hole (small diameter bit such as ~5mm or 3/16” recommended) to prevent the shell from tearing further. The slots can be made with a hand saw or a Dremel tool with a saw blade. It's important to clean up cut edges to prevent unwanted wear and tear of your boot liners. A hooked blade or carpet blade works well. We recommend you start small and slowly make the slots further down for increased flex. We've gone as far as 1" below the pivot point without making the boots too soft. Once the desired flex is achieved, you can prevent unwanted snow from entering the boot by applying tape on the inside of the boot.
Increased Boot Dampness
Drilling large diameter (1.25") holes in the upper cuff is another step you can take to increase the overall flex and overall dampness of the boot. This can be done quickly with the use of a drill and a hole saw. One side effect of this modification is that it can allow for snow to enter the boot. A possible solution to this is to simply cover the holes on the inside of the boot with tape. Newly formed holes should be cleaned up to prevent unwanted wear and tear of the boot liner. A hooked blade or carpet blade works well.