Best thing to clean shizzle with is petrol... so why should injectors need cleaning? It's 100% placebo BS that scams peeps galore unfortunately.
Get 2 mucky pieces of engine-ware and clean one with petrol and one with injector cleaner. So so similar.
Just pay £15 on a new fuel filter, take out the pick up neck - clean it out, syphon out the old fuel (do all this on a really low tank) and replae with 99+ Ron fuel. Then go and give it some 5-6k beans for 20-30 mins. That'll clear her out along with an oil change and air filter.