[Jay]

rather than open air, I opted for a drop-in K&N filter, turned the airbox over, cut a hole through the metal benath and attached a 3' PVC pipe with an angled end, for a sort of cheap ram air system. At the same time I changed the exhaust to catless 2.5". These two things together significantly improved throttle response, and I have beat a couple of later MK IIs since then (they should have a good 10hp on my 82), so I think it was worth it. We tried an open air element on a celica (22R-E) once, and it made a difference to the sound, but not noticable performance difference. I think an intake/exhaust upgrade combination is likely the best idea.