What would be an "acceptable" range of output for a tial spring? In particular the 38mm Big Yellow along with a small green? According to their site it should make 17.4psi, but datalogging shows 14.2-14.4psi. I try the yellow/blue too and same outcome.

There are no boost leaks, and everything holds steady...its just like 3psi off whether I hook into turbo or intake for a pressure source. Has anyone else had this problem? I find it odd that two spring combinations yielded similar results.

 

another possibility is the sensor your using to measure psi is off? just a thought...

 

that is possible. I'm using the GM 3 bar. My autometer boost gauge (even though I don't trust it 100%) reads about 18psi with the yellow/blue springs. Boost cut happens at 22-24psi on the guage but it set at 18.5 in hondata. 18psi from the 3bar reads 20 on the autometer. I guess I'll just try the big green/small yellow and see if that fixes things.