Better than a McLaren F1? You are joking aren't you? To come out with a comment like that means you have never driven one! I have had the privilege of driving several supercars (F40, F50, Diablo, Bugatti EB110 and a few others) and I can honestly say that the McLaren F1 is the best supercar money can buy!
(Of course working for a car magazine and not having to pay for these cars may alter my view slightly, after all paying £650,000 for a McLaren F1 would create definite expectations, and no matter how good it is, it probably won't live up to all of them)
I've actually worked for several car magazines, in several countries and these tests weren't direct comparisons. In fact the Diablo, Bugatti and F40 were grouped together for a photoshoot of Italian supercars, and no comparison test was allowed in the magazine (although we were allowed to test them out on the airfield we were using, for a short while at least). The F50 was loaned to us when the car was launched, I drove it, but didn't officially review it, but still managed to form my opinion on it (you may have seen the photoshoot, it was pictured with Eddie Irvines race car) and the F1 was loaned to us for 5 hours (with various McLaren officials constantly scrutinizing what we were doing, and telling us how the car should be used).
I am sorry to point this out, but this review is obviously a fake. There are no 1990 Diablos, this model was 1991-on wards. And even if the "owner" did not remember correctly there were surely no 6.0L engines back then, they were 5.7 V12s. The bigger engines came only at the end of its career (2000-2002) after VW-Audi bought them out.
At least other "reviewers" take the time to research the history of the model they are "reviewing"...
I was also wondering what was up with the 6.0 Litre V12 in the early 90's, on a stock Diablo. The last Diablo model before the Murcielago was launched, was a 6.0L, but that's it. I knew I hadn't missed anything in my reading:).