You might hear the question is the S58 G87 M2 better than the B58 M240i or is it the other way around? Here is one tuner’s take on the issue.

The S58 car is more expensive, but for the price difference, the B58 car can be fitted with fuel system and turbo upgrades.

One thing we notice about S58s is they are very easy to tune. In particular, stock S58s tune very well up to the 600-650HP kind of number that many daily drivers feel is the Goldilocks value for a daily driven sports car.

The graph below is from a tune we did for a G80 M3. The car has a stock turbo with cats and GPF removed.

The S58, with it’s two fuel pumps, two turbos and lower compression ratio eliminates many of the tuning problems one encounters with its sister, the B58. It is easy to ramp up the load and timing and the engine will respond predictably. The stock fuel system can provide enough E40 to get up to a very high load of nearly 285%. Even at this load, the timing can be cranked up to 18 degrees with zero knock correction.

What that means is you can create an S58 tune in the Goldilocks zone with minimal fuss and no mods beyond a downpipe. Do you want that power in, say, one week, or do you enjoy the process of choosing new hardware and building up your car’s performance? This, in our opinion, is the right question to ask if you are trying to choose between the G87 M2 and M240i.

Postscript

Is there a catch with S58 tuning? There are some subtleties to getting a tune that drives really fast. In particular, S58 tunes with torque below 800Nm can actually be faster than tunes with more torque. At higher load and torque we see S58 drivetrain losses rise significantly. The S58 has a sweet spot in other words. Even though the engine is forged from factory, to go beyond these numbers requires hardware upgrades with steeply rising costs.