Misha,

The reason for removing the pre-heat hose is to prevent the air mass meter from being fried (literally) if/when the airbox thermostat fails. When functioning as designed, the thermostat opens below a certain temperature (is it 32F guys?) to allow for faster warm-up time and thus lower emissions, and then closes once the engine has "warmed up." When the t-stat fails, the air mass meter is treated to a continuous blast of toasty exhaust gases as the t-stat remains in its "open" position.

The turbobricks website, at http://www.turbobricks.org, has some suggestions for improving breathing.