The modern turbo four.

I'm sure it is, but what is lost on me is why many of them sound so bad. And the worst culprits do seem to be from the 'sportier' end of the spectrum.

I think the biggest problem is the engineered in sillyness, which can also make 6 & 8 cylinder engines sound terrible, although they do start from a better base.  As Pete says, GPFs don’t help either.

I was surprised, but the Golf sounds pretty good from the outside at low revs in normal mode, but most will be in race which sounds pretty bad imo, thank goodness for individual mode. I’m not really bothered what a car sounds like from the outside as you rarely hear it and I don’t care what anyone else thinks. Having said that, the 750 sound even better from the outside, but that’s because it’s so refined,. Sport mode helps a lot and thankfully it doesn’t add in any silly pops/bangs/rattles.

That nice sound you hear from a four pot is usually induction noise. The turbo drowns most of that out and it has an effect on exhaust too.

Simple. Modern 4 pot turbos tend to have mani-turbos, where the exhaust manifold is cast into the head and the turbo bolts straigh to it. Older engines had the option of tubular manifolds to smooth out the pulses or even have them work against each other (like the aforementioned Subaru) and experienced engine tuners could wring all kinds of noises out of a 4 pot using exhausts. Induction noise is pretty much gone nowadays, even opting for an aftermarket air filter does next to nothing with modern engines as they are already hugely efficient.

And GPFs, the next big killer of modern engines....

But also, people have been sold the idea of popping, banging and farting as being sporty. Older engines will do that too, but only every so often and usually in a high state of tune, not on every up or downshift.

Decent sounding nat asp 4 pots are long gone and I for one miss that. I've had some belting engines powering me along in my past - every Peugeot 1.9, whether 8 or 16 valve. The Legacy Turbo, the Clio, even the 8v 2.0 in my GTEs.

I keep seeing a Golf GTi in the village, the version where the last sporty one has a six-pot. This particular car has an R32 twin-pipe exhaust, but sounds fucking grim. Loud, which is what the owner was after I suspect, but grim nonetheless.

I think the Abarth I heard only had 2 pipes possibly.

I always thought that the Sierra Cosworth, on a standard exhaust, sounded a lot like my mum's 1984 Toyota Corolla 1.3 

I'm keen to see how we can make the 2.3 Ecoboost 4 pot sound in the Mono. We have a much shorter exhaust system and no GPF. I hope we can make it nice and burbly with some whooshy boost noises.

As soon as we have a running car, I will likely video the first start/run for posterity.

I had a moment there wondering what an "Arbroath Fiat" was...and was thinking one would need a large exhaust in order to achieve the desired smokiness...

I always thought my Golf Mk2 GTI 16v sounded decent enough, as did my old Mk2 1.8GL after I had it fitted with a Weber carb (the original gave up the ghost).

And I never had any complaint about the turbo'd fours in my 2001 A3 1.8T quattro and 2003 S3, but then again perhaps I just didn't know any better.

Certainly after selling the S3, I bought the first Z1 with of course a straight six, and since then I've only bought cars with at least six cylinders. 

It's quite near the local model flying club fields, which are apparently public park land they 'officially borrow' from the local council. I got a flyer about it at East Fortune last year, and the fella on the stand was very knowledgeable and chatty, keen to promote it. On my list for a post-lockdown visit.

I've been to the Montrose Air Museum.... small but very interesting and you get personal treatment

Will do. Do you still have the same mobile number?