We've just had a bit of a play with our Vauxhall VXR8 long-termer, fitting Walkinshaw Performance's Power Pack.

_Y8F9555 The kit comprises a revised air filter, an ECU upgrade and a stainless steel exhaust that lifts the regular VXR8 rumble up to 92dB. It also frees up an extra 30bhp.

Thing is, I've been wondering ever since the car came out of Walkinshaw's workshops if I've done the right thing. The performance exhaust that's been fitted is only the 'minor' upgrade, you see; Walkinshaw also produces a V8 Supercar unit that turns the volume up to 110dB - and accompanies it with a cacophony of crackles and backfires. So I've been torn between driving a car that sounds like a Bathurst racer, and, er, living with one.

Today, I got my answer, for Vauxhall has helpfully fitted the V8 Supercar unit to its latest press demonstrator, the LS3-engined 6.2-litre VXR8. After five minutes I was nearly biting the steering wheel with frustration, because it sounds fantastic.

And after six minutes I felt content. Why? Because I'd started to get annoyed at the intense noise and cabin boom being created by exhaust explosions. Frankly, I couldn't wait to get back into our long-termer, to enjoy the mix of great V8 noise and, er, motorway cruising ability.

We don't do much performance modding at Autocar, and this incident shows why. As it is, we've struck a fine balance and genuinely added meaningful enjoyment to our VXR8 experience. But if we'd ticked the wrong box (and spent a lot more money), we could have ended up with a hooligan of a vehicle riding roughshod over many of the original VXR8's best qualities. Cars are there to be ruined, as well as improved.