Kwak make the supercharged H2, but you're right, no turbos.
I've often thought that they could make smaller capacity bikes with turbos rather than the litre bikes. I guess it's a combination of cost and issues with lag and boost, but you'd think with modern tech they could sort it. With emissions regs tightening all the time they just keep increasing engine capacity to replace the power lost by the mapping for emissions. A turbo could help in this situation, but it's telling that Kwak chose the more predictable power delivery of a supercharger.
Also thought about diesel bikes too. Just imagine the fuel economy..... 100mpg+? I suspect that for the most part in the west, bikes are less essential transport and more weekend fun.. So a diesel would have a limited market. And why go to the expense of a turbo, when many bikers don't care about fuel economy so carry on making bigger and bigger engines. Just my thoughts...
Just recently joined the cliché and bought a BMW r1200gs.