Anti-lag, is a system used on cars to completely eliminate turbo lag. It is a feature of the engine management system. WRC cars are fitted with a class mandated restrictor on the turbocharger inlet and this increases turbo lag significantly. Because of the pressure drop across the restriction, the pressure ratio for a given boost level is much higher and the turbocharger must spin a lot faster to produce the same boost as before.

Anti-lag effectively increases the mass of exhaust fed to the turbocharger. This is typically done by retarding spark timing to a point where most of the combustion happens in the exhaust manifold, typically around 40° ATDC. At the same time more air must be added, this can either be done by the use of a throttle bypass valve or a throttle stop solenoid. When anti-lag is switched on it is typically active when the throttle is closed, and when the throttle is opened the spark timing is resumed to normal.

Exhaust temperatures produced by this system are phenomenal but they can be controlled by varying the amount of fuel injected while anti lag is active; a richer mixture lowers the temperature. Anti-lag is typically only used on race cars because it can shorten the turbocharger service life down to impractical periods for street use. The turbine blade life is drastically reduced, and the entire exhaust system is put into shock, which can lead to explosion or fire

Information above borrowed from oddkiddcreations

Ive just got a P8 ECU with pectel board modified to run ALS, Air Injectors, Water Injection and Dizzyless with the ability to use a Pectel monitor

This will be fitted to my Escort in the new year with the full cossie management, im currently waiting for a maram shaft turbo to turn up which offers additional strength but is exceptionally costly.
Apparently anything but very very mild antilag can serious effect turbocharger life and as such you require the stronger maram shaft.

One thing that people often forget to point out that using ALS on the public highway may be against the law as it can be considered noise polution so you could find yourself in trouble if used on the roads.

I personally do not consider ALS to be cheap if you are going to do it well and invest in a maram shafted turbo.

Talk to Jano Oddkidd about it, hes the fella doing mine