Interesting.
I agree that when the air is cooler then it becomes more dense and therefore you can add more fuel and get a bigger bang. My limited understanding of petrol ECUs is that they can respond to a lot of environmental factors including air density (as it relates for example to altitude) to add more fuel for more power when air is more dense. Those cheap resistor type power hike things do the same kind of thing by fooling the ECU at the expense of fuel and engine life.
Combined with the faster warm up with the grill block and you may find gains there.
I know others have gone on about the K&N and it may work for you. When I used to tinker with my old style Mini K&Ns were fitted but usually had very little if any real effect as it wasn't the air filter that was the worst flowing part. In the case of the Mini the manifold was far more restrictive than the filter. Having said that the K&N made the car audibly faster - as in it sounded sportier and faster. But wasn't really. My old MGB GT will get standard filters back on it when I get time to get it finished.
I would be interested to see what the results of going standard with the air filter and removing the cool intake (as you have done) but leaving the grill blocks in place are.
I'm not trying to discourage here - you have got on a lot further than I have managed so far with mods. I'm very interested to see how far this can go.
