I have the Seine Systems Gate Shift Kit installed on my 915 and I absolutely love it!
But - this is not only thing changing the game!
I also had to overhaule the bushings on the whole shift linkage including the shift coupler in the rear! My car already had the Porsche short shift kit. It works very well together with the GSK. Not to forget a proper adjustment which is required while driving around and adjust several times until the perfect adjustment has been found. I carried two wrenches within the car to adjust it from time to time...
I find it much more easy to handle/shift now, now more comparable to my other cars whose gear shift levers also tend to go in the 3./4. alley automatically.
But - and I cannot emphasisze this enough - the right gear oil is on a 915 the by far most important "component" affecting the shifting and handling comfort! Because most of the people fill in these gearboxes modern oils with lower viscosity than Porsche originally specfied! POrsche specified for the 915s an old SAE90 GL5 oil.
If the viscosity is lower than this, e.g. 75W90 and a probably also a modern (partially-)synthtetic oil, then the required drag torque of the 915 is not available and therefore the synchros of it cannot do it's job. And this also heavily affects the shifting comfort as well as well finding the gears...far more than expected!
My recommendation is, if you do not know for sure what kind of gear oil is in yours, refill the 915 with a mostly mineral old school gear oil of SAE90 GL5 and test it again. See this video, he uses a
Swepco 201, it's available in SAE90 and SAE80W90,
both the SAE90 meets the specs of the Porsche recommended
Shell Spirax MB90 (don't know if this available in the US, here in Germany only in unhandy and too large 20l barrels):
https://www.youtube.com/watch?v=cOV0_bt1xRY
Edit: It has to be an API GL5 oil for the 915! Don't know if AGMA 4EP of the Swepco 80W90 meets this....
Happy X-Mas!
Thomas