4 hole spacer ona single plane

You will get a better idea of what works or doesn't when swapping intakes and/or adding/removing spacers if you have the opportunity to try different jets. It's not easy, but changing something like this can affect the optimum jetting and squirters for that particular combination. In other words, you change intakes, but the new one may require more carb jetting when it was "optimium" with the previous intake. So just swapping intakes may lean the engine out and it looks like the new intake is down on power. The bigger the difference between intakes or spacers, the better the chances of the carb needing to be recalibrated.