The first time you exit a tight corner with a hint of opposite lock and keep this 500bhp supercharged HSV nailed deep into three figures lives with you forever. The exponential lunge of acceleration is stunning, the rise of the rev counter needle matching the increased intensity of the torque and power storm. It's the sort of power that demands total concentration and a healthy dose of restraint. But when the opportunity arises to wring out the HSV it's an absorbing, thrilling and slightly scary experience.

Over the last couple of years HSV has made a name for itself in the UK as the creator of cut-price M5 rivals. The 401bhp GTS-R matches the German icon for sheer performance and its chassis balance can teach the Munich uber-saloon a thing or two. At one point the GTS-R was nearly ΂£15,000 cheaper, too. That was before 'rip-off Britain' became such a buzz-phrase. One by one the manufacturers dropped their prices and now the ΂£50K GTS-R doesn't seem the bargain it once was. Still cheaper than the M5, but only by ΂£2000, the GTS-R has found its market drying up.

The less powerful GTS is still doing great business, though. At ΂£39,995 it makes a lot more sense and its 340bhp should be plenty for most reasonable people. But for unreasonable people HSV UK's servicing arm, Linden Special Vehicles in Northampton, can now supercharge the GTS in return for ΂£10,000. That's creeping up into M5 territory again, except that the M5's 400bhp starts to look pretty puny when the supercharged GTS flexes its muscles.

Owners will have to put up with 'only' 340bhp for the first 1000 miles as the standard engine is run in. Then the supercharger, which runs at 0.5 bar, and intercooler can be fitted, with awesome results. Power is up to 502bhp at 6050rpm and torque leaps from 350 to 457lb ft - higher in the rev range (5100rpm versus 4000rpm).

The GTS has had a raft of styling tweaks for 2002 with new bumpers, side skirts, rear spoiler, front grille and headlamps to give it a sharper edged, more aggressive appearance, which is undeniably menacing if not very subtle. The chassis lacks the GTS-R's more sophisticated multi-link rear suspension arrangement and Hydratrak diff (as used in TVRs) but with an effective LSD the big HSV does a good job of putting all that power on the road. The switchable Racelogic traction control previously seen on UK HSVs has been replaced by a simple factory-fitted on/off system. Amazingly, in the dry at least, you'll rarely feel it intervene.

Rather than a sudden rush of torque, the supercharger keeps the same linear curve as a normally aspirated unit. There's more of it, sure, but it's predictable and progressive in its delivery so your right foot has a precise input into what the car is doing. The HSV's weight and size mean you can't take too many liberties, but if you're sensible it's possible to make ruthless progress.

Thing is, the GTS's playful nature means that sooner or later you'll stop being sensible and start really enjoying yourself. The extra power means that if you so desired you could drive everywhere with a twist of opposite lock. The V8 has plenty of low-down power so a satisfying slide can be provoked and held without ever unleashing the truly angry horses at the top-end.

Most of the time the LSV-converted GTS drives much like the standard car. Fast, grippy and huge fun. B-roads reveal admirable stiffness and great body control. The massive brakes (343mm cross-drilled discs front, 315mm rear) are tireless and bite with conviction right at the top of the pedal travel whilst the steering is accurate, weighty and surprisingly direct. The six-speed manual gearbox is a bit ponderous - but what do you expect when it's handling 500+bhp.

It's when you're really committed that the supercharger makes a difference. Find a good road, use all of those revs and the blown GTS is devastatingly rapid. For those who have sacrificed a TVR for a growing family the pumped-up HSV could be the perfect tonic. If you're after big fun with four doors, the supercharged GTS has got everything else licked.