The type of arm has no relation to fps rather what type of bucking you are using. If you have a bucking with a nub style of \/ \/ (as in a Firefly, or a MGunner said the PDI W-hold) then get the flat nub arm(type B), however if your nub is more like the stock configuration, or a Nineball, like this ')' (picture that turned 90* to the right) arm, use the type A.
In regards to the TDC mod, you could remove the head of the screw sticking up if you used a grub screw instead*(credit to CheeseMan for the idea) and then either leave it dialed in with the bb weight of your choice, or drill a small hole just large enough for an allen key in the RIS to be able to adjust the hop.
In regards to the TDC mod, you could remove the head of the screw sticking up if you used a grub screw instead*(credit to CheeseMan for the idea) and then either leave it dialed in with the bb weight of your choice, or drill a small hole just large enough for an allen key in the RIS to be able to adjust the hop.