those woodpecker gates are what i use also. much better than the rockler slide gates by far. one thing i see is your using sharp 90 degree elbos and t 'S. i did the same until i read about how much your air flow is cut down. so i changed where ever i could to using 45 degree elbo's and sweeps. it all adds up especially when you have long runs like i do. 

working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.