Mac,

There is no problem with you increasing the response time. What will happen as you make it faster and faster is you will see the throttle arms moving back and forth arround the "sync position". The faster you go the more the arms move. It tends to blend the RPMs together so that you might not be able to hear the osciallation (because that depends on the response time of the engine) but you can see it if looking at the throttle servo or throttle arm.

Another important thing to remeber is that when you are testing response time settings you need to test it at several different throttle positions. The Walbro carb is very sensitive from high idle to just above half throttle (this is why they are so difficult to sync mechanically or with curves). I also hear that pop-off pressure settings have a ton to do with mid throttle response. So just be sure to try it out throughout the throttle range after changing response time - since the engine response time and rpm change per 1 degree throttle servo movement is different through out the throttle range. (not to give away any secrets but the response time of the twinsync is different based RPM/stick position).

As for a "Y" cable. Yes you could use a "Y" cable off any channel. However, it seems to me that you would want the TwinSync turned on during approach and landing. I guess you could turn on the landing light once on the ground?

As for RPMs during a loop.... Let me explain how the twinsync works and then maybe we can figure it out. When you move the stick the Twinsync disengages and moves both servos to the new stick position and then after giving the servos enough time to move there (assumes about 0.3sec/60 deg) it starts the sync process. The sync process speeds up one and slows dow the other equally until they are synchronized.

So I would actually expect the reverse... A good test would be to put it in a dive and throttle back to mid stick. I would expect the RPM to be higher in a dive at mid stick than in level flight at mid stick. The reason is because it is easier to speed up and engine in a dive than it is to slow it down. So if left throttle servo pulls back 1 degree and right throttle servo increases 1 degree I would expect more of an increase on the right than decress on the left in a dive compared with level flight.

Play with it in a dive compared with level flight and let me know.