Lamborghini Gallardo > Murcielago in my honest opinion, but murc isn't bad, just not Gallardo good,
really any classic italian car seems to sound good, i haven't heard one that would deserve less than a 9/10, even from my super-critical ears
Zonda is good, but Enzo sounds better, F50 is interesting, but is almost too high-pitch sounding for such a wide (big) looking car
E60 M5s with stock headers and opened up exhausts sound like F1 cars, which is cool
, the Eurosport header also sounds like V8 esqe, and i rather like it.
E46 M3s have really really crap exhaust notes (too raspy) but the overwelming intake noise is very good, i think thats what people are usually listening to when they say "i like the way a M3 sounds)
cars i been around in real life? Drove a 1992 Race prepared Alfa Romeo Spider (2.0 TwinSpark engine) with custom exhaust (forget specifics) Driving it was pure joy! it was the first car ive ever driven that made me deliberately speed just so i could listen to its engine. The guy who owned it now has a 1968 Barracuda which sounds equally as good, but in a different way
4ages (old toyota 1.6ltr) do sound good in various applications, im designing and building a header for my MR2 which should sound very very good (spent alot of times studying the dynamics of header sound, and i have been blessed to be in contact with a lead tech advisor from Flowmaster!)
C6 corvette at Grattan Raceway sounded awesome in front of me (most cars at track-days have forgettable sounds, this one didn't)
Cars that disappoint me? Lotus Elise, especially as i know the engine supplied in the car can sound wonderful, as illistrated by various MR2 spyder engine swappers. 350Z sounds almost fake to me, like when one says a girl looks "too plastic" that is how i feel about its exhaust noise. BMW Z3 M was suprisingly dull for being a convertable. and most subarus sound too much like farts for my liking, dispite all my freinds thinking that their the shizzat (even the muscle car guys)