PTFE gaskets have the benefit of helping to prevent thermal transfer between castings, and are re-usable, unlike the OEM steel gaskets, reducing heat and lowering costs.
During development it was also found that the steel gaskets would often loose boost under pressure testing. With them replaced with the Orranje PTFE gaskets, this is no longer an issue, as they create a complete seal, ensuring boost is used, not lost!
Please note that it's not uncommon for MINI castings to have excess material, which differs from casting to casting. Due to the gaskets being thicker than standard, to further prevent thermal transfer, you may find the excess material can foul slightly on other castings once the gaskets are installed. To solve this issue, simply clean off the excess material using a file etc.