I had the same problem with 17 plate TE bought in March 2017, got hotter as time went on , and by April time it was so hot that it felt like the sole of my right boot would melt , sent it back to the Dealer for investigation , they said it might be the fan ( but it wasn't) and sent it back , no fault found ? After two weeks I was still being roaster alive ,so back it went this time the Cat had got so hot that it had turned Blue with the heat. Dealer swapped the front pipes + cat from their demo and also removed my Mudsling to let some more air circulate I guess, whilst it was a little bit better you still couldn't wear summer pants or summer boots as the heat was still uncomfortable. After talking to the Dealer who was in contact with BMW UK & Germany ,it transpires that this issue is known( not so much in the UK I'm told), and not all bikes are affected and surprisingly my mates GS TE ( month later build date has no issues), so after another 4 weeks had passed I was informed that because BMW couldn't fix the bike ,my bike would be swapped for a New GS TE same spec as before with no cost implications, collected said bike in late October 17 and have had no heat issues whatever , still don't know what was the cause of the fault , but fair play to the Dealer & BMW they came good. just to say the original bike was completely standard with no tuning/mods etc.,