Today, it finally clicked and I’ve figured out the tuning secrets of the Borla EightStack. I knew how important the linkage settings are and how sensitive they are. I was spending all my time to get the idle right but had overlooked the importance of checking at higher RPM’s. With a little trepidation, I set the RM to 3,000 and checked the airfow. One side was 11, the other side was 18. Obviously, the cross-linkage was off. But why, it was OK at idle. Then I realized at idle, some of the blades may be resting on the venturi bores and unloading the linkage. 

I adjusted the cross linkage at the higher RPM (remember, it’s very sensitive) and after a couple tries, SUCCESS! My cross balance airflow matched at idle, 2000 rpm, 3000 rpm and 3500 rpm (Chickened out for the higher settings)

The secret – do the final linkage tune at higher RPM’s and have to guts to let the engine run up higher while you’re adjusting it.

So happy with the results, I posted more details in the engine section (Borla EightStack Tuning)