According to this Motorcycle.com article from today, the specs are in on the new 1300 boxer engine. Presuming there are no tweaks between the GS and the R, these are the numbers we can expect…not significant on paper, and I wonder if the real-world feel is at all noticeable:
“According to the Swiss homologation data, the new GS claims a peak output of 143.5 hp at 7,750 rpm, an increase over the current engine's claimed 134.1 hp at 7,750 rpm. The listed peak torque also shows some improvement, with the documentation listing the R 1300 GS at 109.9 lb-ft. at 6,500 rpm, compared to the R 1250 GS' certified 105.5 lb-ft. at 6,250 rpm. The documentation lists a top speed of 140 mph, compared to 136 mph for the current model.”