Might want to check out
this page, where you'll find a CO2 pressure calculator widget that you can find numerous styles of beer with the associated carbonation ranges. You can then use the "canned" value for any style, or you can manually set the desired carbonation level and temperature, to pop out the right pressure to use. Witbiers classicly approach four (yes, 4) volumes of CO2, making it one of the most effervescent of styles. At a carbing/dispensing temperature of 35°F you could set a pressure as high as 26 psi. That said, it's always brewer's choice in such matters. Pretty much regardless, if you use steady pressure at dispensing temperature it'll take a good two weeks to fully carb a five gallon corny keg of beer of average FG (add more time for big FG beers like imperial anything)... Cheers!