I've just been looking up injector part numbers on Rimmers site for the petrol engine.
On that site they list 3 injector types for the petrol engines:
MYJ100430L [coloured yellow] suitable for the 1400, 1600, 1800 & VVC - to year 2000.
MYJ100640 [coloured black] suitable for the 1400, 1600, 1800 & VVC - from year 2000.
MYJ100580P1 [ coloured blue] suitable for the 1800 & VVC - from year 2000.

Other than colour, what is the difference between these Are they interchangeable? Do the later black / blue ones deliver advantages over the earlier yellow ones?

Up to 2000 worked with a dizzy, 2000 on worked with coil packs, so I imagine the ecu were slightly different

So I have a limited knowledge of the K, so take this with a pinch of salt.
MYJ100430L for a K with a dizzy, will under fuel in later engines.
MYJ100640 for ECU controlled engines, will over fuel at low speed and under fuel at high speed in a dizzy engine.
MYJ100580P1 no firkin idea
There's loads of different injectors for the K, if you want to be baffled go on the Lotus forum, amazing what those guys can do with a humble K series.
Mike

I have a 98 MGF VVC which I'm thinking of breaking this year. So if you want some low mikes VVC injectors, give me a PM.