If I use lamps it will be before the air filter. I'd rather have it behind it, as it would keep the lamps clean and doesn't need heating up; but there is not enough room.
At least the lamps will be air cooled so they probably will not burn out even when slightly filthy.
Even if you believe in the positive effect of swirling the air before sucking it past the intake valves, if the swirling takes place before the air filter I cannot see how that would affect anything past the filter.
My ABABABABA testing will consist of switching the power on the heating device on a cold start, or not switching it on. Any swirling caused by the design shoud have the same influence in the A and B scenarios, whether it is positive, negative or nonexistent.
Got an inflammation in my shoulder joint, on sick leave at home as I cannot drive. But it is already waning. Just don't expect me to jump in the garage and build my heater right now
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.