http://www.ebay.co.uk/itm/polo-mk4-6n-1-4-...0#ht_500wt_1070

saw this on ebay, never heard of anyone running 1800 golf injectors in a valver...?

I saw that advertised and did think the same, dont see why you'd need them or what theyd benefit? Pretty sure theres enough potential fuel up untill about 130-140bhp?

I'm running afh injectors on my 1.6 and they are coping fine with 137bhp. 4 branch isn't going to give much if any real gains and the golf injectors ain't gonna do any thing positive (might even make it run worse) so I call his claims of how fast it is pure bullshit, probably hasn't even driven a polo GTI

Makes no sense. The computer will realise it's overfuelling and compensate, the best that can happen is it'll run normally.

Put a 1.6 bottom end in a stock valver, you've got over 130bhp and the standard injectors are fine. Induction kit too, they'll still keep up.

So if you're not getting upwards of 40% extra air in your AFH, what do you expect to gain with bigger fuel injectors?

Makes no sense.

This. ^^^^

The computer will realise it's overfuelling and compensate

Mostly. Where it runs closed-loop fuelling chances are it'll have half a chance of pulling the fuelling back towards lambda 1, but there are control limits imposed in the software to stop the ECU from dangerously leaning things out in the event of a knackered lambda sensor. In practice it might not be able to correct sufficiently, so you'll run too rich on partial throttle/cruise wasting fuel and will gradually fuck the catalyst if you've still got one.

On the 6N it's still open-loop fuelling on high load/full-throttle, so there's no feedback for the ECU to correct the fuelling. In these conditions it'll overfuel nicely, probably running a fair bit richer than the optimal mixture for peak power. So you might lose a bit of power, and economy will suffer.

To summarise...

the best that can happen is it'll run normally

...and I think that is being optimistic.