Tacoma?
Looks like they have 70A alts regardless of which engine -- not much firepower for a good sized sound system.
1000w rms isn't huge, but with an alt like that you could have some issues.
If the alt turns out to be inadequate trying to solve it with a cap would be like bringing a match to a flame thrower fight.
Initially, I don't think I'd buy anything until you get it installed. It's not unheard of for an amp that size to run ok on a seemingly small electrical system. Your listening habits have a lot to do with it.
However, be prepared for the possibility of an alternator upgrade. I saw some 130A listings on ebay for $110+ship which would be a significant upgrade.