I've read lots of different articles on TB spacers, air vortex devices, etc. I must admit, I'm not convinced that a spacer will give you enough insulation from the SC to make a bit of difference, especially looking at the cost of most of them and the fact that they are 1" or less in depth.
If you really want to keep the TB cool, build an aluminum shelf that sits below the TB and above the crossover pipe. If you have that aluminum shelf a couple of inches below the TB, the air space will help as an insulator and it will keep the radiant heat from the crossover pipe from adding additional heat to the air charge.
Consumer reports did a test on several of the 'vortex' type devices that are supposed to increase your MPG and HP, and those they tested did nothing more than lighten your wallet.
Don't buy into the hype!