Anybody care to explain why Neptune have Primary (High/Low Ignition & fule) & Secondary (High/Low igniton & fuel)? If tuning ignition or fuel for the low cam do I just use the Primary LOW ignition & fuel? and not mess with the HIGH on primary?

 

Thats a secondary map for like race gas etc. Dont worry about it if you have no need.

 

You can swap to secondary maps on alternative race gas or eE85. So you can have two fuel/timing tunes