That's wrong, DSI is a feature to improve the airflow to the engine and therefor to improve the engine performance. It is just a common misconception that it would hide the engine from radar waves and has something to do with RCS reduction, but it hasn't. JF17 has a Y-duct to do so, but that or the limited use of composites in Block 2 can't compensate the lack of RAM or coatings, which is the key feature to achive a lower RCS for any 4th gen fighter, be it for a newly developed, or an upgraded like the F16s, or Mig 29s.
That's where LCA has an advantage, since it was developed with a low RCS as a major aim and no matter what went wrong during the development, this field actually was pretty successful. The knowledge ADA, NAL, HAL and co. gathered wrt to designs, materials and coatings will be highly valuable for any future aircraft projects!