Modules research cost

I’m researching the Z-10ME, and since it gets a new ATGM at rank 4, what will happen to the rp if I research the TY-90 before the patch? As far as I know, it should become cheaper, since at rank 4 there will be 4 modules instead of 3. So should I wait for the patch or will there be compensation?

It will be cheaper but not more than Rank III, I’d suggest going for TY-90, it’s a very potent air-to-air missile and the AKD-10 still useful despite the velocity.

Compensation is only applied to removed modules and other exceptional cases, I may be wrong but I don’t remember any compensation in this case.