The 944 isn't like most cars, things are pretty optimized right from the factory, and historicly, they just don't see the gains typical in other makes.

The 911 E and S that are classed for ITS are even worse off, as getting more HP from them is even harder. I doubt you will see many...if any...of them, and certainly not at the front of a top notch grid, as the spec weight is just a tad too high to warrant the expense.