The original Renix injectors made by Siemens-Deka were only “one holers”. That means the fuel was discharged through only one hole.
Not the most efficient design by today’s standards. Modern injectors have at least 4 spray holes for better fuel atomization.
Another issue is the original injectors were prone to leaking fuel at a seam and spraying gas all over hot manifolds. Not good!!
A nice upgrade is to use Volvo injectors. The use of these injectors was pioneered by Programbo from Cherokee Forum when he suggested them to DFlintstone there. Flintstone was the guinea pig and reported excellent results. I have experienced the same results as have many others. The 746s, as they’re called, have the 4 hole design and the complete Bosch part number is 0 280 155 746.
These injectors can be purchased refurbished for not much money and are a direct bolt-in.
You will experience smoother idle and better throttle response. Perhaps some MPG improvement also.