I just bought orange top four hole injectors and my vendor cuts a slot in the correct location of our injector rails.

 

I installed a set of design III in a 944 and I had to cut slots. I used a hack saw because it's easier to control and cuts a cleaner slot that the dremmel can.

Use 19lb injectors if staying stock or go to 24lb injectors and sharktune away.

The 24lb set I used in the 944 are purple/pink Ford Bosch injectors which have IIRC 6 holes. So far they have worked very well and improved idle substantially with the finer atomization they have.

 

I have stopped selling the design III because there are so many variations with or without the correct slot for the lock ring to the injector rail.
Some have a larger diameter at the top which is not so apparent even if you stick to the correct Bosch number. This looks fine until you install the lock ring and it bulges and does not hold the injector correctly.
Stick with Design II if you do not know what you are doing.

 

What a fantastic thread!

Based on the information in this thread I decided to pull the trigger on some new injectors, rather than refurb my old injectors (in the middle of intake redo). I liked the idea of the improved fuel atomization of the 4-hole spray pattern over the single hole injector. I noted the concerns about variations on the design III and potential fitment issues associated with the groove for the retaining clip. However, I decided to go with these Bosch 0 280 155 884 Design III injectors and verify the injector clip.



I received the injectors today and gave them a test fit into the the fuel rails and they seem to fit perfectly. I used a little synthetic grease to make sure they were properly seated. The injectors came with the 928 specific 16.5mm lower O-rings too.









Monday, I'll bring them into my friends auto shop and we will bench flow these against my stock 150K mile stock injectors. I'll post a video for your viewing pleasure

 

Hi Michael,

Did you ever get the video done...? Would love to see it.