The opinions on this vary from one end of the spectrum to the other. Clearly almost everyone here has NOT had a good experience with the valve. But, I have heard some people say that after installing it, they saw a 2-3psi increase across the board, and smoother onto boost transitions. Don't get to excited though, 2-3psi on these tiny turbos is good for about 5-10 crank hp MAX. Again, I've heard some people say that this is a very worthwhile mod, others bash it to no end. I think if you do the basics (intake, TIP, exhaust, etc...), the J valve will show itself a bit more. I plan on doing it as soon as mine comes in, as I've already ordered it, but it is on backorder.
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