It is my understanding that the P-160 has been temporarily discontinued for new sales in the US. I am pretty sure JetCat will continue to sell them outside of the JetCat USA territory. I am sure Bob will announce something when he and John get done touring the country (driving back from Superman).

I do know Bob is still supporting the motors, with the latest change being a 12 stick combustion chamber. They run awesome but I think are not economical to produce and support in this configuration.

As for the MkI versus MkII I will let Bob spell that out when he gets back from Superman. I am trying to find a good used one right now myself. I have 2 MkIIs and will put the new 12 stick chamber in when I get a chance.

As for some of your other questions.

Yes a P-160 can be used in a P-120 pipe.

All of the updates had to do with containment of combustion within the proper region, as the P-160 has very high exhaust gas velocity (VERY high). So with a P-160 it is much more crucial in terms of assembly, etc to get one to run right...there is very little margin for error. THerefore it was difficult to get the reliability up to the level of say a P-120. That is why they were derated in the US, in an effort to improve reliability.

Along the way these motors had new EGVs, modified bearing retention, and now new combustion chambers. There are/were more things coming down the pike if they ever re-enter the US market, but those things might go into some new motor, I am not sure.

These 10 to 1 thrust/weight motors are not easy to make!