Just add some 5K ohm resistors in each earth line to injectors, this will take it up to around 8 ohm which is plenty ok, Karl himself told me this as this is what I use, on my greys.
Don't even think of approaching 100% duty cycle, try not to go over 80%, if not just ring emerald, speak to Kim or Leoni, 01953 889110, as they also sell suitable injectors.
By the way it's not the first either, or the 2nd or 3rd!!
tabetha