Better to be safe than sorry.
On a side note, iraggis are known for their durability and performance by the bass heads on other forums so if you have a decent stereo, power everything, electric fans, etc it would probably be a good investment to keep your battery charged.
Main reason I posted this thread was to show they do infact make HO alternators for z's. I believe iraggi is the only one that sells true Ho alternators for z's.