I guess the question is, if something breaks, what can you fix?
If you know your car, you'll have an idea of whats been changed, whats on its way out and whats likely to fail.
Last year we did a trip round europe in a mates bora, we did the ring, various mountain passes including stelvio and about 4000miles.
When we left, we asked ourselves "what can go wrong?". We decided the only two possible failures were clutch and turbo, as everything else had been serviced, renewed or was extremely unlikely to fail. Clutch you can drive around if it starts slipping, so that leaves turbo. We figured if it blew, we'd just block the oil feed line and drive on naturally aspirated.
On the third day, half way up umbrail pass, on the way to the top of stelvio, the turbo let go and dumped two liters of engine oil into the intercooler and exhaust in an impressive cloud of smoke.
So, at the side of the road, half way up the mountain, we blocked off the oil feed line with a screw and some superglue, repiped the inlet to suck directly from the air using a couple of the intercooler pipes and a pair of tights. Then realised we had no engine oil and the level was off the dipstick. Luckily we were with a group of folk, and some passing folks lent us the couple liters of oil we needed to get going again. After a few hours we realised something was pressurising the sump and had blown a liter of engine oil out the breather all over the engine bay. Eventually figured out the exhaust was pressurising the sump thru the oil return on the turbo, so we removed that and superglued another bolt over the oil return. Drove the rest of the trip with a naturally aspirated derv which had about 40hp and exhaust pouring out of the turbo compressor housing, but no other problems