The present invention provides apparatus (100) and methods for testing for leaks in forced-induction internal combustion engine (10) air intake systems. The apparatus (100) includes a plurality of work faces (132n) each having at least one flange (134n) disposed thereon for attaching the apparatus (100) to an air intake system of an engine (10). An air flow valve (136n) is disposed on each work face (132n), those valves (136n) being moveable between open and closed positions. The apparatus (100) also includes a compressed air supply inlet (138) configured to supply compressed air to the air flow valves (136n). Wherein, compressed air can be supplied to the air intake system of engine (10), via an open valve (136n) which is, in use, internal of the intake system, enabling a simulated air pressure test to be performed in order to locate possible intake system leaks.