Me think the picture I remember was from a test in Echappement that came out when the Golf2 Gti was released. The 16v was not out yet, when did it come out again ? It was a 16s in France, S for "soupapes"

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Plus, Yacco was a French brand, so I suspect it was more of a dealer's thing.
The compartment I remember, it was held by a rubber strap and looked very much OEM. Vertical, on the left.
However, looking at all the pics of a Golf2 trunk that I could find, I wonder if I'm having false memories or something. There's no molding for an oil can behind the driver's side rear wheel arch...
View attachment 271890
I remember it just under that pannel with the switch. Aligned with the fender, held by a rubber strap.
Eh, well. Maybe the pic was under a different angle.
PS: There was a Golf I Gti 16s Oettinger in my neighborhood... a relatively beaten up daily driver. That was before people had decided whether it was an ugly unicorn or rare unobtanium... Jury's probably out to this day. But it was for sure a nice feat from VAG France.
Mr Oettinger was also a colorful individual. A genius tuner, sometimes impulsive as a businessman though. Word was he had a mountain of expensive, order-built crankshafts in his small factory, as he had heard that there are tax restrictions on large displacement engines in Portugal (cutout was about 200cc lower than whatever VW was making as bread and butter at the time), and decided he'll build a bunch of VW engines that displace just under the limit. Then it turned out things were not exactly as he imagined them.
Or was it the opposite - was it that he ordered stroker crankshafts that would make a 200cc higher displacement on a Golf, but didn't account for the tariffs... Can't remember. I'm getting old. One way or the other, he ended up with an order of many mucho crankshafts he had no use for.