the article is one year old but the valid objections of IAF are still Standing :-
top IAF officials argued the FGFA has "shortfalls… in terms of performance and other technical features."
Business Standard has reviewed the minutes of that meeting. The IAF's three top objections to the FGFA were:
(a) The Russians are reluctant to share critical design information with India;
(b) The fighter's current AL-41F1 engines are inadequate, being mere upgrades of the Sukhoi-30MKI's AL-31 engines; and
(c) It is too expensive. With India paying $6 billion to co-develop the FGFA, "a large percentage of IAF's capital budget will be locked up."
the IAF renewed the attack in a MoD meeting to review progress on the FGFA. The IAF's deputy chief of air staff (DCAS), its top procurement official, declared :
the FGFA's engine was unreliable, its radar inadequate, its stealth features badly engineered, India's work share too low, and that the fighter's price would be exorbitant by the time it enters service.