I think I'd rather keep my standard rubberised pulley wheel over something I've read so many bad things about. Smaller lightened ones were effective on old sports cars like the MG, Jag etc but modern designed motors don't really need them.

The Subaru intake was supposedly good for 15hp, I doubt there is a massive difference in the cheap ones as far as air flow.

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Beaten up old 98 Gen 2 Liberty, 13.0, stock V3 STI running gear.
07 Transit motor home
69 VF & 70 VG Valiants needing full restoration
Yamaha Zooma 50cc rocket hopefully going with the Transit.