I am probably just misunderstanding some numbers. Without having KSP open, I was looking at the thrust on the jets compared to stock. The rapier stock is around 400, while some of your engines were around 2,000 and unlocked earlier. I think I am missing something. I am an English professor, not a scientist lol. I think I need to play around with them more to understand what is going on.
Also, if the "OP" stuff is unlocked late in the tect tree, especially late in the CTT, I have no problems with it being "OP," because that is what the higher techs are supposed to be.
Great mod though. I have this and the MK3 installed. This is going to be a fun playthrough