How is the Pre-Heated Exchanger outputting 149 out of 103/s?

Baked into Factorio:

• Baked-In Factorio assumes 200J to heat 1 unit of fluid by 1°.
• Baked-In Factorio assumes all fluids begin heating at 15°C.
• Baked-In Factorio assumes it can dump its entire [Max Consumption (energy)] per process cycle.
• Moddable The [Max Consumption (energy)] property of an entity, i.e. Boiler at 1.8MW, or Heat-Exchanger at 10MW.

This allows entities to derive:

• Their maximum [Output per second (fluid)] based on [Max Consumption (energy)].
• Their current [Output per second (fluid)] based on the rate needed to spend their [Max Consumption (energy)]

Maximum [Output per second (fluid)] Example (using regular steam boiler):

1. Boiler heats 15°C water to 165°C steam, [200J * 150 = 30,000J], or 0.03MJ per unit of fluid, every second.
2. Boiler heats with 1.8MW. [1.8 MW / 0.03 MJ] = 60 water/s.
3. Factorio 2.0 requires 1/10th of the water to output 1 units of steam, so [6 water/s == 60 steam/s].
4. 6/s input : 60/s output is now our maximum [Output per second (fluid)]

Current [Output per second (fluid)] Example (using modded Pre-Heated Exchanger):

1. Exchanger heats 165°C steam to 500°C steam, 200J * 335 = 67,000J, or 0.067MJ per unit of fluid, every second.
2. Exchanger heats with 10MW. [10 MW / 0.067 MJ = 149 steam/s].
3. 149 steam/s is now our current [Output per second (fluid)]
4. 103 steam/s is now our maximum [Output per second (fluid)] (assuming we do the same math as above for the regular boiler).

Why not adjust the [Max Consumption (energy)] until it shows a proper 103 out of 103/s?

We can try, but remember that [Max Consumption (energy)] is used in both in Maximum and Current [Output per second (fluid)] and it will adjust both values to give the same ratio as 149 out of 103/s --> 103 out of 71.1/s

Are you sure this isn't a cheat entity?

Yes, the energy consumption and fluid processing rate - while weird to look at - is above board.