After reading this thread I added 1.6 mm thick Oring. I did not see large bowing effect from this small Oring. This is probably due to the 1mm gap that already exists, so the compressed oring is just filling this space...But my temps improved 1.5 degrees.

So this means that the Fuzion can be improved without bowing and with out adding jets. So if you are not someone who want to bow his base they can get better performance... If I had a thicker O-ring I would get the bowing effect and probably have even higher improvement. How thick is O-ring you are using. (I did not get o-ring from barb, I have a metric O ring kit and this is the only size that would fit)