From a Russian site, when asked about India's contribution in PAK-Fa:
"The Indian input will be just great relative to other Indo-Russian joint ventures till now.
1) Almost all composites on both version, since India has for now more advanced manufacturing line for composites.
2) Two-seater avionics.
3) Most of electronics on FGFA version. Including Radar's DSP. Hardware and especially software/
4) FGFA final engine will be per Indian choice, so probably being MKIsed western or Russian engine, difference in nozzles could be too.
5) The well expected in 10 years Naval versions will be probably even more different. "
"Progressive composites - is a half of project success since payload, stealth and airframe life are heavy depended of it. I think, everyone must do what can do the best. It's a key for competitiveness. If some avionic kit can be developed and produced in India - it's welcome. Otherwise, in India will be produced those parts, which is economically worth produce in India, and which is worth in Russia will be done there. It's depended of manufacturing effectiveness, what I want to say. THey will look for private sector submanufacturers in both countries."