Chrome boxes don't retard the timing at high rpm.

Orange boxes DO.

Orange boxes are also much more failure prone.

If you have to pick between the two, spend a couple extra bucks and get the chrome box. It's worth it.

But that said, when my pile ran mid 12's I once A/B tested orange/chrome boxes and saw no difference in ET, shifting in the 6000rpm range. It's very possible that certain combinations might actually run better with a high rpm timing retard than without.