This is all true with the timing. As my Snap-On scanner has shown. The HHO causes the timing to lower and sometimes retard. All done right by the computer, NO added electronics. My feed lines are to the vacuum line for the brake booster and a port in the air duct just outside the throttle body. I use 3 back pressure valves($ 5. a peice at Advance auto parts) to direct the flow, one at each line connection and one between the tee and dryer. This is so that i keep the most vacuum on the system at all times(throttle open or closed)! The reason for 3 valves is because you will get a bypass of vacuum into the intake thru the lines if there not back-flow prevented. I have my flashback arrestor and a solenoid(GM evap solenoid), between the gen and the single back-flow valve. The EVAP solenoid is connected in series with my gen relay so if my gen is not on then there's no vacuum pulling on anything.
Its done right or its not done !
Hail HHO.