HB 150 engine can be fine tuned between 1200 HP and 1500 HP. It depends on the balance of life span and mobility.If the weight of the tank is 52 tons, then a 1300HP engine gives it a power to weight ratio of 25 (same as AlKhalid). That's pretty good. Infact it's almost as high as it gets for tanks anywhere in the world. And considering the opposition it's excellent. No indian tank even comes near. So I would agree that 1500HP engine is not needed, especially if it comes at the cost of other parameters as you mentioned.