This Vauxhall XE is available in 38mm and 42mm sizes and is port matched to the cylinder head, no additional manifold is required. With the throttle blade very close to the inlet valve the engine response is lightening quick. The 38mm version is optimum for 2.0 engines running below 230bhp, and the 42mm version is ideal for 2.3litre heavily modified engines upto and including 300bhp.