Basically yes - x8.

For more info please see:
http://www.cartographersguild.com/sh...ings-explained

Section 11 onwards. Maybe you can try some of the newer fancier resampling options out there now. Resampling upwards is always a limited exercise so for this reason always make any maps at as high a res as you can stand if you think your going to want to do that in the future.