TGV to head gaskets: 14035AA421 vs 16272AA001. Any experience?

[mx5]

I am converting the engine of my '05 OBKXT from side feed to top-feed injectors (boost is going up soon so I need bigger injectors)

I am using the TGV and OEM fuel rails from a later engine.

 

While browsing the part numbers I noticed that for the early cars (like mine with the side feed injectors) the parts listing for the gasket between the TGV and the head is 16272AA001 and is called insulator.

 

For later LegacyGT/OBKXT (with the top feed injectors) the gasket is listed as 14035AA421.

 

Any idea why Subaru switched to these thinner gaskets?

I got a new pair of each to compare and 16272AA001 are much thicker pieces and have lots of rubber on both sides. The shape is identical thus both types look interchangeable. I would imagine the thicker ones with the rubber might keep the engine heat off the TGV/intake manifold better.

 

So ... with the top-feed TGV should I use the thinner gasket or keep my original thicker insulator style? I am currently swayed more towards keeping the thicker one, but have there been issues with those for the change?