My mate has a Escort Cosworth fitted with an anti-lag system. The system on it keeps the engine revving at around 1.5-2k when idleing but the pipework under the hood bypasses the inlet of the engine from after the turbo, essentially dumping the boost through the exhaust. There is still a noticable lag on the system, not majorly but if running a smaller turbo (250-300bhp) the results would be better, his is rated for over 400bhp. It does a good job but side effects include a super hot engine/turbo/downpipe/exhaust. The CAT which was initially on the car was burnt out within a couple hundred miles. And the heat generated has made the paint crack on the bonnet near the twin vents and over the turbo. The system is switchable, otherwise the cost to run it would be immense.