To space or not to space
It all depends on what kind of spacer you are using. If you use a spacer with 4 throttle holes in it, this will tend to help your bottom and mid range power, with little or no help on top end, where a spacer with an open plenum, or big hole will tend to help your mid and top end, with little or no help to the bottom end.
The reason the 4 hole will help bottom end is that it keeps the velocity up at lower rpm, while the one hole jobs act to increase the size of your plenum chamber ( or chambers if you have a dual plenum intake), and large plenums are very useful for high end power increases.
The one with the one big hole, would probably have more effect on your engine, particularly on top end than the 4 hole variety would on your lower and mid range. The thing to be careful of is that while it may help your top end, the one holer may harm your lower end power. Its all a matter of compromises and what your desired end result may be.