i got a set of apexi n1 pro dampers w/ custom spring rates. i was just wodering when do i kno when its time to send them out to get rebuilt? is there a guideline as far as month, year, miles put on them that i should get them rebuilt? thanks

 

They are not limited by time because nobody knows what sort of conditions the suspension is put through, but you. 50k miles on smooth stretches of highway are gonna be easier on the suspension than 5k miles of straight track time.
Unless you are able to notice a drop in performance due to the wearing out of your parts, then you do not need a rebuild until the shocks are blown, IMO.