Once an airframe is developed, there are limits to what changes and improvements can be made. And we DO NOT want to use Singapore's F16s we just know everything to there is to know about that plane. We also had 6 years with the most advanced variant of F16 for our MMRCA competition and evaluated it on more than 600 different criteria, and rejected it. We know all about that plane. It's a good plane but ultimately it's old.
And no F16 is no match for MKI and we don't need to deploy all 300 for pakistan.