The filter housing in the 156 is located below and slightly behind the headlight. If you remove the housing then it will be fairly isloated from warm air. The cover should be fitted towards the engine side to deflect heat away from the filter. Also, try to keep the intake pipe (the short pipe that feeds the airbox) in place to provide a feed of cooler air. Directing a pipe to the front could work but allow enough room at the end of the feed pipe for water to escape during a rainfall without reaching the filter as this could potentially destroy your MAF. Sand shouldn't be a problem because that's what the filter is there for. To stop sand. And dust, etc.
Don't over-oil your filter as excess oil may also be sucked in and destroy the MAF.
The best move would be to fit a K&N direct replacement filter, then fit the GTA intake pipe to the airbox. This pipe has a much higher flow capacity and will allow more air into the filter box, unless ofcourse you are already driving a GTA
which doesn't seem to be the case from the pix provided
Hope this info helps!
