The dreadful knocking and how it happened

Hi everyone, after reading many threads of engine failure and experimenting it myself, I wanted to show how it happened and hopefully, how I end up fixing it. - The car - This is a 99' C4 Cab (Tiptronic) with 100K miles I bought last year. The previous owner said they just had the engine rebuilt by a Porsche specialist after it blew up. I don't want to include too many boring details, but at some point I picked the car up from the shop where they did the engine work and drove it home, so the engine was just broken-in according to the shop and the previous owner. That's when trouble began: The car had a pretty bad intermix (not present when I picked it up) and the convertible top didn't work. So right at the start I knew the car was in not such a good shape as advertised. I'm actually involved in legal actions to either get rid of the car or the issues sorted, but that's gonna take a while. Despite the intermix and the soft top issues, the car wasn't running rough, so I continued to drive it (the shop owner told me to keep driving it, and that they would fix it whenever they could as the car had a warranty). - The moment everything went wrong - After 1000 miles or so, I was commuting to work, and right before arriving I hit the gas while exiting a roundabout (I didn't even floor it really). The car was up to temperature, the g forces were nothing crazy, and it was probably a matter of 2 seconds, but while I was exiting the roundabout, I saw the pressure dropping to the 2, and after that, I started hearing a noise at the back like when driving over gravel, like little stones hitting the bumper. Luckily I was already at my destination, so I parked the car immediately and listened near the engine bay. This is the sound it made just as it happened: You Tube Just a light, intermittent tapping. But I couldn't leave the car there for long, so after around 30 minutes of calling the shop and having a coffee, I started the car up and parked it properly. It just took a minute, but the noise difference was very noticeable, now it made some sort of high pitched noise along with the tapping/knocking: You Tube After that, I didn't plan to start the car up again, but the shop owner asked me to remove the auxiliary belt and see if it was any accessory making the noise. This was one hour after the last video, and the knocking is intermittent: You Tube Then, they asked me if I could trace where the sound was coming from... Obviously I don't have the skills/tools to do this, but I recorded a little video from underneath the car, with the belt still off, where the tapping/knocking is still intermittent: You Tube When I had to leave, I had the car towed home, so I just started it to the tow truck and then from the tow to my parking spot, this is the "final" noise that it made, that hasn't changed since: You Tube I had no idea what was going on with the car at that moment and the shop where they did the engine work was like 300mi away, so I took it (again, towed) to a mechanic I trust. When the car arrived and they started it up, they were very confident on it being rod knock, and said that by simply pulling the sump, there would be some debris confirming that. Well there you have it, this is from the bottom of the sump, but there was more like this in the oil filter. There was more debris in the oil pickup tube: Apart from that, visual inspection revealed a broken spark plug tube and very old, cracked coils. From that point on, the car was never started again and it's sitting in my garage waiting for this mess to be solved. I'll update the thread if I get to pull the engine and see the actual damage, and hopefully post the cost and means of solving it. I guess you can learn lot's of things from my experience. First, even if a supposed "specialist" is servicing the car you bought, take it to another specialist for an inspection, I was stupid to believe that just because of it being a very well regarded specialist in the area, the car was going to be immaculate, wrong. Then, whenever the first issue appears, stop driving the thing. I know a car with intermix is not supposed to be driven, and that the oil in the rubber hoses is only going to cause more damage, but it was on the shop's responsability as they told me it was fine, so I kept driving it. Maybe if at the first sign of intermix I took it to someone to take a look at it and drop the engine to fix it, they would've noticed that the engine condition was very poor. I hope the videos with the noises are helpful to someone.