what is stage 3? how do you measure stages? I think the word 'stage' is an exremely ambiguous term.
Specifications are what determine what will and won't work for your motor.
The word 'stage' is a poor way of describing an item because what is 'stage1' to Apexi, may be 'stage4' to Greddy... see what I'm saying.
A 16g or T3/T4 description would be a better way to gauge what will work (which would fall into the realm of specifications
)