Direct Injector Cleaning Fuel Additives, any good?

[tawa 150]

My N55 equipped X5 has always had a small stumble at mid load low/mid revs. The wife reckoned it was quite bad on a long trip last week. No codes etc so I figured I'd throw some DI Jectron at it. Can't find any in NZ, is there anything else worth using that might make a difference? Mileage is about 150k, always had BP 98 in it when I've owned it. Ease of throwing something in the tank vs removal to clean vs cost of new ones makes this the first step if there's a chance.