So, modifiers that only can work with bullets and/or rockets.

I would not mind to much if their could be special types of bullets that could do fire or electrical damage at the cost of a module slot.

Rockets on the other hand already do heat damage though... So adding the ability for them to do electrical and heat damage at the same time may be a little to much. Then again, it would take up a module slot that could be used for something else...

Now modifiers to decrees the amount of heat or energy used may have it's uses. Maybe make it reduce the amount used by a percentage rather than a fixed number.