I've been talking to Chris (LateModel21) about the boost levels we're seeing, and I guess 20PSI is the max we're going to get with the 61.9 EC pulley. I saw 18.8 PSI this morning (55F) at the top of 2nd, which would likely be approximately 19.8 PSI at the top of 3rd.

For some reason, I thought this pulley was going to make 22psi, but it's not.

Here's Chris' notes on the subject:

"Stock boost 14.5psig ("pounds per square inch gauge" ie, pressure ABOVE ambient) + 14.7 (air pressure above a vacuum at sea level .... ie "1 bar" aka "1 atmosphere")
= 29.2 psia ("pounds per square inch absolute" ie total pressure above a perfect vacuum)

29.2 psia x 73.6/61.9 (stock pulley diameter divided by new pulley diameter) = 34.7 psia

34.7 - 14.7 = 20 psig = 20 psi boost

so .... if your can generate 14.5 psi (psig) then changing the sc pulley from 73.6 mm to 61.9 mm should get you up to 20 psi. This is assuming pumping losses are the same ... these losses should however increase (as a percentage) as boost goes up so 19.5 seems reasonable"