Assault spring for TIPPMANN 98 class of markers - the maximum velocity one, but snipped shorter to fit the 98.
Can possibly be modified to work w/ BT as well as the TiPX
Works 100% - inserts in behind the rear bolt, replacing the less stiff stock one.
This spring allows to rear bolt to hit harder, thereby allowing more gas per shot to enter the chamber. Use this in conjunction with turning the velocity screw open (clockwise for most 98 markers, counter-clockwise for the TMC, however, if you do not have a chronograph, keep a record of how many turns you turn. Usually 4 - 5 full turns is enough)
The ideal would be to use a chronograph to measure the uptick in muzzle velocity - using too much gas for a slight boost in muzzle velocity isn't worth the trade-off. Get to the ideal spot where the optimal boost is reached, by not sacrificing too much gas per shot - that way, you enjoy high velocity plus moderated gas loss per shot.
Use this combination ideally in conjunction w/ solids - this will dramatically improve their trajectory and efficiency, as well as allowing them to strike harder.
These should function nevertheless with paintballs, even the rainbow variant, and shouldn't chop them - nevertheless, use at least 2 star balls if you intend on shooting paint with your upgraded muzzle velocity.
Note that upgrading your paintball marker for defense / counter-riot purposes means that you will not be able to use your marker for paintball games.