Although it's not a cetane booster but Marvel Mystery Oil has been performing better than Power Service with our 7.3L lately.
The place I get Power Service from by the half gallon is about $12.50 and the Marvel Mystery Oil is $17 for a gallon same location.
The Power Service makes the injectors alot louder with the 7.3 versus using Marvel. I should take a photo of all the additiives on my Diesel shelf