honestly i never even seen the check valve...i just put mine right ther the right one i put more to the left (closer to the bent part of the line)..and it works just fine been like that for months. i went by streetunits dual valve setup kit
i read someones thread and i guess i misread it. i put mine closer to the actual brake booster on the fire wall. and now my boost gauge is not showing boost and my hks is not doing its thing. i felt the check valve and put it to the right of it. but that one diagram says not to go past the right of the check valve.
u put the boost gauge on that vacuum line coming off the brakebooster? i dont think ive seen anyone doing that. usually they just 'T' it in on the intake manifold the little hose by the throttlebody..showed in bumpin_p5 post#2