Yeah I wasn't recommending it. Merely showing what was available.
You'd probably get 2-3 of these filters for the price of one of a decent cone that'll last for ages. Just don't see it myself. Nice experiment though. A huge green cone filter cost me $40. Doubt I'd get an s2000 filter here for $20.
Those gains you got may well be from the removal of the heat shield. They sit very close to the filter which has to effect flow a bit.