It would be very hard to say I would think, unless you hear an obvious lope. Mine makes an obvious lope, its a moderate cam setup. If the car is running in top shape, you should make around 18-20 hg vaccum at idle. With a different cam you can notice less vaccum at idle. I notice less then 10 for the most part with mine.
You really can only use the boost gauge as a reference if you are 100% sure you have no vaccum leaks, and you have to remember the stock gauge is not 100% accurate either.