good question.....we has been experience before.it will be depend to the installer how there do it. but the correct way is arm the alarm then the engine still running after just switch off by the timer.
This is kind of air booster, it keep extra air in the black thing....so when u revv,instead of sucking hard for fresh air.it wil easily get air from there. aftermarket air booster is way too expensive, so DIY is...