You don't even understand the point I'm making, so I'm not sure whether its worth continuing to argue it with you.
When you drive a £10,000+ car why paddle through an oily workshop round the back of a pub after dropping off your sports car to then walk to the bus stop whilst the 'boys' from the garage swoon over the fact they've never seen anything with an engine bigger than 2 litres before and take turns in bouncing it off the rev limiter when instead you can either:
a) Pop it into the dealer and drive off in a 60 plate loan car
b) Pop it into a reputable specialist for whom the car is just another 350Z and therefore not like a red rag to a bull.
I've seen the reaction you get in places like Kwik Fit when I had tyres fitted to a perfectly ordinary BMW 5 Series, let alone a 350Z. It was like I'd turned up in a freaking Veyron. It was ridiculous. Whilst I'm sure there exists the odd backstreet place with only mature and talented individuals, there exist many more full of complete chimps with the business skills of a squashed fruit. I can't be bothered with the risk, and if you have £10,000+ of 350Z, neither should you.
Obviously Nissans quote on this occasion is ridiculous, so take it to somewhere that knows 350Z's and pay less and get peace of mind.