the reason for cost escalation for the Su-30MKI's is airframe to be modified to include reconfigured air intakes and internal weapons stowage in the underbelly. Both upgrade proposals are essentially selective applications of technologies now being developed for the PAK-FA and PMF/FGFA. The stealthy Su-30MKI has been designed for specifically for two tasks: retaining the edge in beyond-visual-range air combat despite the availability of hostile AEW & C capabilities; and the destruction of hostile ground-based air-defence networks/systems. However, for these two tasks to be executed, one requires a new generation of long-range multi-mode BVRAAMs (like the Meteor) and standoff PGMs (both anti-radiation missiles & small-diameter loitering PGMs equipped with tri-mode seekers). Development of these two types of weapons within Russia has fallen behind schedule, but will likely be available by 2016. Only by then will the stealthy Su-30MKI option be seriously looked at by the IAF. At the moment, though, the Boeing F-15SE has the upper hand as it is being made available for immediate export. @bharat h-rakshak