Placing an exposed filter on the throttle body would be a bad idea indeed, i wasn't suggesting someone should do it, was just trying to make a point that one could do whatever he wishes as there are few limitations. Whatever placement one would choose, he should build an airtight box for the filter, otherwise he will see little or no gain from the colder and/or higher pressure air, and just benefit from a possible decrease in flow restriction if it is the case.
