I've had a JHH Kfir C2 now for about 6 years and 260 flights. Has the foam wing (42") with elevons at 11.5 pounds dry. Has flown variously with a OS.77/Dynamax, OS.65/Dynamax and currently on a OS.91/Ramtec (by far the best setup I've had in it).

Based on my experience, you will likely be disappointed using the 7.5/Turbax combination, particularly if you are looking for the performance current jets have. Use as much as you can get in the plane. The plane is draggy with the nose up and you have to fly through the corners as it can burn speed off in a heartbeat. But it will float nicely dead stick if you keep the speed up.

My plane was radar gunned at 145 mph in a dive with the OS.65/Dynamax. It was faster with the OS.91/Dynamax, and when working right, is even faster with the OS.91/Ramtec/BVM pipe. As Jack Jet said, it can be fast with the right power package. Of course, it's not a BVM Viper/Bandit either.

You have to set it up on the gear so the nose is at a positive angle, otherwise, it takes a huge amount of elevator to rotate (I know). When I put the Ramtec in the airplane, I covered the cheater hole in the wing - you don't need it. I also got saddle tanks in the fuselage next to the exhaust duct and a header tank ahead of the fan - 6 minutes with a one minute go around reserve. Springaire retracts with 3/16" struts.

Good luck!