Carrera vs RS, RSA?
 

I am rather new to the World of 964 an I would like to know what the difference is between this models, that is what kind of modifications is causing the difference in power? 250 -> 260 hp?

The difference in power is because of engine selection, on an assembly line there is a range of performance, by choosing only the best for a particular model like the RS they can advertise it.

the other differences are mostly in weight, trim and suspension, C2 and RSA are the same except for some small weight reduction in the RSA-optional sunroof/AC etc.

RS has a much better suspension for performance or track use and much better brakes

The difference is in the software programming. The RS has a chip that runs 3 degrees more ignition timing advance across the rpm range from 3000 rpm up, increasing the power by 10 hp. A simple change in a non-RS car with just a different chip can achieve power levels and response equal to or beyond that of the RS.

If that is so then why do both the M64.01(normal) and M64.03(RS) have the same DME?

I do believe that the timing and map is likely more aggressive as the RS is spec'd for 98 and the C2 95 octane, it's true that the DMEs all contain multiple maps that are accessed via jumpers in the harness, perhaps that is the answer

I'm not sure about all the different DME numbers. From all I've seen, all the ROW RS have a unique DME number, which is because of the DME and unique chip inside it. The chip inside is not interchangeable with any of the other 964 DMEs across the standard 964 range - the car won't start if you do. I'm guessing this was done to prevent proliferation of the RS programming or unapproved chip swapping.

Whereas all the 964 DMEs across the entire span of standard non-RS cars are essentially the same and interchangeable. Only the chip inside has had about three revisions from the 89 to 91 model year. The early 964 units in 89 did have a fuel quality switch, but other than that has no operational difference.

interesting.
good info.