There's no doubting that Anti-Lag System (ALS) sounds really cool both but they are not road legal for one very good reason - braking power is greatly compromised due to ALS taking up most of the vacuum. We have quite a number of WRX and STi running ALS and there had been many near misses because they owners thought it was cool to show it off on the road but didn't realise the car nearly had no brakes.
Here's a pic of the PossumLink ALS aluminium "choke" adapter. This device is specially made to ensure the throttle butterfly valve is opened at around 30 TPS while the ALS chip does the rest of the fuel and ignition timing trickery. This cable runs to the throttle butterfly and goes to the spare slot to which Cruise Control is fitted.
Another downside to running ALS on extented periods is not only the turbocharger suffers damage from excessive heat, the entire gallery where the hot gases travel post turbo is affects too. ALS also damages exhaust manifolds and dump pipes. I have personally witness a JUN ex. manifold glowing red hot within just 30 seconds of activating ALS and this was from a cold engine!
To give you an example of the power to do damage from an ALS, we smoked two 450-hp Garretts in a very short time. But there's plenty of power to be had from ALS, it's simply breathtakingly. We had an STi 4 Type R running stock VF24 turbo and with ALS, the car spun all four wheels while the catless exhaust was spitting flames several foot long.
So yeah guys, if you have the money and itch to run ALS, it's FUN while it lasts, coz it never does!
Jan