[yobbo]

Looking at pictures, it has two visible round jet nozzles which suggests it has much higher radar cross-section and IR-signature than F-35.

[greedo]

It's extremely difficult to evaluate RCS by looking visually at an aircraft. Who would have thought that the F-117 would be stealthy? And the reason the F-35 only has one engine is because it has a much higher thrust than the RD-93 on the FC31. This increase in thrust "might" increase its IR signature, and neither has any IR shielding like on the F-22.