Whilst no doubt tudei kavas can be very strong, strength and painkilling properties do not define them. Some tudei's - and I would say most, in Vanuatu at least, are no stronger than other noble kavas, but just make you sick as hell the next day. Not the normal " kava hangover" that even the best noble will provide if you overdo it, but a real full body sickness.
The strongest most pain relieving kavas I've had have been noble , like from central Tanna or southwest bay on Malekula.