This is AMD's stage 2 conversion - the stage 1 simply concentrates on the ECU reprogramming - and costs ΂£2144. That's quite a lot of money but for the performance gains alone it seems wholly reasonable; throw in a fully stainless steel exhaust that looks fabulous, is quiet at cruising speeds and suitably furious under full acceleration and the kit looks remarkable value.

AMD is best known for its work on VW Group products but it now works closely with Vauxhall and knows all there is to know about the VXT's 2-litre turbo engine; so much so that when Vauxhall started work on the VXR220 project, it went straight to AMD for the engine programming. So it seemed the natural choice when we wanted to give our VXT even more performance.

The graph in the magazine shows that the torque curve is seriously pumped-up by the conversion. This means you can often stay in a higher gear and just surf along on the swell of mid-range grunt and still make indecently quick progress. If you choose to stir the gearbox things get very busy indeed. In damp conditions the extra power means you need to give the VXT more respect; third-gear corners that once would have been negotiated with mild understeer can now turn a bit hairy as the torque gets hold of the rear wheels and sends them fizzing sideways. In the dry there are no such worries. It will oversteer more readily than before but the chassis still feels remarkably composed and traction is very good despite tyres that are rapidly getting down to their wear indicators.

Just how much faster our Vauxhall is post-tuning we'll discover soon. I figured the car in standard form a few days before the tuning work was carried out and will repeat the test when I get a few minutes spare at Millbrook. Even on a blisteringly hot day and with a shade more mechanical sympathy than I might employ on a test car, 'my' VXT hit sixty in 5.1sec and 100mph in 13sec. That's mighty impressive, but I have a feeling that the figures will tumble significantly now that AMD has had its wicked way with it. I'll let you know next month. In the meantime I'm off to pester Vauxhall about that trick Ohlins suspension set-up that's optional on the VXR220...