Redex contains a whole bunch of solvents that dissolve just about any type of gunk you might find in your engine. The main ingredient is Kerosene (paraffin) but it also contains acetone (as in Hammerite thinners/nail varnish remover), toluene and xylene.
It will dissolve gum and varnish, just because kerosene/acetone/toluene/xylene do dissolve gum and varnish. Whether it's any use or not depends on how bad your fuel system is in the first place.
I would use it, whether your car is injected or not. The Redex for injected engines might contain a different proportion of the different solvents since injectors might have different requirements to carburretors.. but frankly you have all sorts of stuff in different brands of petrol anyway.
Your car won't notice that the Redex is "supposed to be" for a carburretor engine rather than an injected one and it won't harm it... there's nastier stuff in petrol basically.
These products are all 90% kerosene, so if you want to clean your fuel system through in future, why not just use Kerosene? You can buy "Turpentine Substitute" (
not White Spirit) from Homebase, B&Q, Focus (not Wickes, strangely) etc. and it's neat kerosene.
Stick 200ml in every full tank of gas. It does 90% of the job of Red'.. but £3 for 2 litres, against £8 for 500ml...
Ralf S.