Im going to replace my current intake system with one from Kansai Service. To understand the reasons for changing; read this article. Although I have the carbon housing I still needed the actual filter. HKS & Greddy make universal mushroom filters that fit the housing and are cheaper than their full intake kits for the swift. Since my current setup already has a MAF housing pipe (coming from a K&N 57i kit) I decided to buy the filter separately. It also allows for selecting my own colour silicone hoses and pipes to connect everything together.
I chose the small Trust (Greddy) Airinx B-type filter, which is oil free. I went for the 60mm neck it thats closest to the 63mm MAF housing pipe. I also added an extra replacement foam filter so I can change it up if needed. Below a video of the unwrapping process.
Differences between HKS and Greddy mushroom filters
The filters are practically the same size, but HKS offers more variety in the filter element. They offer 2-layered oiled filters (red & yellow) and they have a 3 layered dry one (green). The HKS filter has a steel cage, the Greddy Airinx Type B filter has a plastic cage. The most important difference between the two filters is the neck. The HKS filter has a hard plastic neck which should be connected to a silicone hose. The Greddy is rubber (see video) so has to be connected to an aluminium tube. I didn’t realise this when buying, but I can imagine this will influence your decision.
AY-SB filter with 60mm neck: 12500301
Replacement filter: 12500013