Mine is very smooth. I took a trip through the mountains of Maryland and PA to the Delaware Valley Olds show this past fall. Some of the roads were through steep country,and I had both my boys! and some travel gear in back. I have a ’62 Borg Warner 4 speed back behind my rebuilt engine – I never really had to get out of 4th gear, even though some of the hills were quite long. At about 2800 RPM, if I put my foot into it, I get a very smooth (it doesn’t feel like I’m waiting a second in mine) jump from vacuum to boost. It will boost up to 6 if I need it (but I never really have). Usually at about 3-4 lbs of boost the car has overcome whatever power it needed and it just levels out. Two things to know about my engine – it’s got a Crower 260 degree cam, ported heads, backcut valves, and the crank and all internal parts were balanced within a gram by me – and with the 4 speed I think that’s why I don’t need the boost all of the time, but when I seek it, it’s definitely there. Stewart Warner sells a pretty nice little boost gauge that I mounted on top of my console, so I can watch when the engine is operating on vacuum, at zero, or dips into the boost. I like to monitor everything in the car when it’s running, so that’s a pretty cool thing to me, especially since my “Economy/Power” gauge isn’t working.