run rich? not really. it will run rich for a split second until you accelerate again, so difference is neglible.
the stalling seems to be mroe with the louder 'ricier' BOV's. so despite the fact they sound rediculous this could also put u off buying a blow off trumpet!
SAFC and most other fuel controllers will fix this and gain power, which has been well documented
the std BOV causes problems as well, it leaks boost. it was designed to run on a std car, std cars run 7-8psi. when u start getting up around 1bar it will leak, causing more problems. replace it!