Perhaps I should have been more specific about the size of the foam tubes. If we choose the 1/2 inch tubing then the coverage may not be sufficient and gaps may remain. Instead, I would recommend getting the 3/4 inch foam tubing as it fills the gaps more thoroughly.
When cutting the foam segments it helps to make sure we cut to fit and that we cover every point of entry - it is not too hard at all and it helps to bend down and check with a flash light. Personally, I get good results and I have been unable to think of a more discrete and affordable/flexible solution.
Blocking only the radiator works very well but it does very little for the air intake temperature. Simply put, the temperature thresholds that determine the level of IMA affinity are derived from a combination of temperatures iAT, cWT, and to a minor extent the oAT.
One advantage of plugging the whole front bumper is that we basically allow more warm air to be retained in the engine cavity thus raising the intake air temp iAT (and oAT) as well. Anyhow, the main temperature value that determines whether the "Auto Stop" engages is still the cWT (coolant temp) which must be at 70C (158F) for it to engage when the iAT is at 12C (53.6F) or less.
At the moment our temps here are at -25C (-13F) and the "Auto Stop" still engages just fine when the proper temps are reached.
Cheers;
MSantos