I concure with Jake on this one. Do it right the first time. Even though you say you're only going to run under 10psi, you never know when you might want to turn it up a notch, or the boost could spike. Its cheap insurance and doesn't hurt anything.
Jake - One question I have been meaning to ask is if you placed the seam of your wire adjacent to a head-bolt? I noticed in the picture its not. Since thats obviously the weak-point in the o-ring, it's suggested to place it as close to a head bolt as possible for the strongest clamp. I'm sure it's better than no o-ring regardless.