15psi, if we are lucky. It seems that Mazda has trumped Mitsubishi with making the most useless stock BPV. It doesn't hold shit. Some people are showing actual horsepower gains and jumps in boost pressure just by switching out the BPV. I'm looking at HKS and Forge for that.
As for power gains, like I said, its just the cat back, so I'm not expecting anything more than 10-15whp and 5-10ftlbs out of it. People going full turbo back are showing 25-30 for each.
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2006 Redline Red Nissan 350Z Base
K&N|Falken
I am just that JDM tight, yo.