I recently decided to buy a 3/8" TBI spacer since they're on sale at Turbo City. I know that they are generally considered unnecessary for our cars, but I figured I'd try it out. I also know that it may be hard to install, but I'm willing to try it. My question is just regarding it's design. I've noticed that the Turbo City spacer is open/siamesed in the middle, while most other company's spacer is separated with two individual bores, just like the TBI unit itself. Is there a specific reason for this? Is one design better than the other? I'm just curious about the difference. I figured that the open/siamesed might be a better design, since the air/fuel is allowed to mix sooner, but I'm no expert on aspects such as this.

Here's what the Turbo City spacer looks like:


Here's what most company's spacer looks like:


So, what do you guys think about this?