Don't spacers go INTO the feed neck of the hopper? Doubt anyone's going to notice the fashion statement there
I had a Custom Products spacer on my hopper for my impulse. It was pretty good, but started to make my rev crack because it was a tid bit tight.
Electrical tape is great because it is cheap and you can actually adjust it. Spacers usually only come in two different "sizes" per spacer. One of the sides is thicker then the other.