I had an interesting discussion with Karen at Aviation Products this afternoon. The catalog page that is displayed on the website referenced in an earlier post is a photocopy of the ACS catalog page, and ACS only lists a 10 deg. angle for the rod style spring that Van's uses while I measured the angle of my Van's unit at about 18 deg. Karen told me that they can supply 10, 15 or 20 deg. units. After a discussion with the guy who designed them, I opted for the 20 deg. unit for my RV-8.
If you order this unit you also need to tell them that is is for an RV as Van's uses a .635 diameter spring and Aviation Products will ream out their unit from their standard .625 to .635 for you.
Really nice people and easy to deal with.
RV-8 82080 Finish/FWF Kit