intercooler

[Dave]

There is threshold lag, and inertia lag, both dictated from exhaust gas velocity. One from engine rpm, and one from actual combustion. This is why teasing them with clutch can get them on boost quicker A big big turbo wont get on boost as quick after a gearchange even though its past its threshold, because its waiting for combustion to happen aswell, the whole system has much more mass to move in the turbo. Hence why adding a charger etc helps because you get combustion to aid in exhaust flow bringing a larger turbo on way before it would normally on natural engine flow.