Frankly the quality of the stainless 6 branch manifolds are not that great; it's been proven multiple times that stock manifolds flow much better, especially if you have them worked on.
Regards to the air intakes, the BMC CDA filter is still a cracking filter; i prefer to house mine internally so as not to suffer with heat soak.
Lastly; with respect to coolant hoses, have a look on ebay at the G Plus VR6 coolant hose packs for around £60. They take 5 weeks from China but the quality is fine. Been running mine for years