that's totally dependent on your setup,experience level,box,tuning,wiring and planned usages.......
but if you plan on daily beating it id say a 1-2k per coil would be fine
burps up to 5-15k per coil
it has 4" aluminum coils and they can take quite a bit, the suspension and cone should fold before you put too much power to it unless you clip your amp and send dc to it for an extend time then it will just melt the coil or tinsel leads.