I have Asus xense Headphones with a quality sound card and trust me this sounds pretty damn good..(and that's through youtube) as you say, there is a different sound for off throttle.. and this car is a hyper car with straight pipes, so it's going to sound distorted.. ever been to an F1 race? Your ears bleed.
I've never been to a race, but I've stood right next to one maneuvring and within 15 feet of them at full chat, I know they're loud. But this is turbocharged and has only one "straight pipe" going by the sound (I know the actual car in the game has twin exhausts, but that's not how it sounds), so it shouldn't be quite as loud (indeed, at least 600 hp is taken out of the exhaust, so).
Besides, it's not even the right
kind of distortion: an ear is not a microphone, nor a digital level limiter for that matter.
I'm using monitoring headphones, though.
What I want to know is why it sounds the way it does when no other car does, unless you factor in their in-engine hard-limiting - clipping; i.e. somebody set the volume ridiculously high without checking the mixer wouldn't molest it (or did it deliberately...).
It's far too dirty-sounding anyway to be an F1 style engine, those things adjust fueling and ignition timing / energy faster than the spark discharge through the plugs! It sounds more like it's got mechanical fuel injection, when really it's probably just another one of those rough, part-throttle exhaust recordings we've come to know and loathe.
But if people like it, then fine. I don't think it's as good as we could / should get, that's all.
So it turns out the car was obtained by patching the savegame for credits (not very observant, am I?). Not really a hack, but whatever...