Even that will have to wait for the new engines. Because IR suppression could cost up to 15% to 20% of the engines output. This is something the Z-10 at the moment can ill afford.
It's not that I don't believe you, because it sounds somewhat logical, but can you share a source as to why IR suppression would result in reduced engine output? From what I understand, IR suppression on helicopters generally is done via mixing cool air with hot air -- this would add some weight to the helicopter's take off weight, but I don't see why it would decrease the actual turboshaft's output.
IR suppression is meant to reduce the temperature of the gases produced by the engine, as I understand it... theoretically that should not influence the actual shaft power already generated (in the case of turboshafts).
If you're talking about generated backpressure from IR suppression reducing engine power then that is another matter, but then that isn't necessarily related to the engine's output itself... and I've seen nothing about 15-20% reduced engine output. One design does state a 3% in engine output due to backpressure though, here:
I believe that means different IR suppression methods would have differing degrees of backpressure and thus differing degrees of reduced engine output penalties, but a quick search turns up no 15-25% reduction in output.
This article below is an informative one (from a Chinese author at beihang university no less!) that discusses various methods of IR suppression on helicopters... and even after a search on other sites, nowhere have I seen any IR suppression method which reduces engine output.
So I'd be very interested as to where you're pulling the 15-20% figure from.