I had a query about the spacer kit, is that a 12mm spacer can only fit? And do I just have to buy the ceramic gasket stuff?(

It depends on the type of SIDI V6 you have : *If you have a LLT engine (early 3.6L SIDI V6, which you can fit extractors to this engine), then the highest you can go 6.35mm manifold insulator without the engine cover. The kit you would need for this would be MI621, which includes 2x 12mm spacers and gasket sealer. *If you have either LF1, LFW or LFX V6s engine (which you can't fit extractors to this engines), then the highest you can comfortably go would be 12mm with the engine cover. The part number for this kit is MI628, which includes 1x12mm spacer, bolt pack and gasket sealer.