You buy a launch controller and the system is installed in your car 24/7, I have seen people rig their MSD ignition to a switch (not the smartest idea IMO), This is a system that is integrated in with your ecu (just like hondata, it has it's own little fancy box) the way a launch controller works is when it's in "standby" mode and it senses the Throttle Position Sensor go past a certain percentage it activates itself and keeps your RPMs at a pre-designated point by killing the spark (like a rev limiter) but while it's doing this, it also dumps hella fuel into your cylinders causing an excess of fuel that isn't being used, causing a build up of atomized gasoline in your exhaust system. This (with the help of your launch controller's ignition timing) causes quite a few explosions in your exhaust manifold and assists your turbocharger to spool up or keep it spooled up between gears.... this is almost exactly what ct9a gsr said.