I have been doing some research and I have found that the inlet manifold insulator isn't compatable with my VY as another guy bought one for his VX and the gasket left a section not sealed and caused dramas with his car is this true?

If you attempt to install a VS-VT manifold insulator on a VX-VY, then a portion of the mating face (between the manifold runner and plenum chamber) will remain exposed to atmosphere resulting in a massive vacuum leak. In summary if you select the right manifold insulator to suit your engine, then there won't be any issues. Please note that we carry both types of insulators in stock.