Since you referenced the Van's article on HP limits, Vne, and TAS, I assume you are concerned about Vne as a function of altitude.

Vne (Redline) for the RV-9/9A is 210 MPH TAS/182.5 KTAS (although you wouldn't know it from official Van's literature). The table on the left in the chart below shows Vne in terms of IAS at different altitudes for a Vne of 210 MPH TAS/182.5 KTAS.

Vno (Maximum Structural Cruising Speed) is 180 MPH

**IAS** for the RV-9/9A. Note that at 10,000 ft, Vno is about equal to Vne. Above 10,000 ft, Vne is lower than Vno and governs.

Hope that helps,