Rich,
I changed my sprocket's out to 18/43 and now very noticeably have this lag both in activation and increase. Obviously because the less RPM in 6th gear. With stock sprockets, it was fine... not now! I picked up a 1-way check valve today and will get the PVC for cannister this week or so.
To confirm, the check valve let's the air flow into the cannister and servo, but NOT back into the vacuum lines, correct?
(Then the servo can steal from the cannister and engine at the same time; k, guess I'm just talking through this.)
I'll help you install it, should be no prob on a VFR I would think..!! Seriously though, if you are going to keep the viffer and do some long distance, this thing is very nice to have Cabinfev....