About the only thing known to really go wrong with a M20 at all, isn't it?

Or ripping up a timing belt and smashing itself to bits. Or bending the crankshaft.
Other than those minor things, it's a pretty bulletproof engine.

Ah yes... well the timing belt thing is a bit obvious, and I doubt that's an M20 only thing... the crankshaft business does sound really nasty though

It's only a problem when you exceed about 420 lb-ft of torque, so it's a problem specific to me and about 15 other cars in the world that have well-enough breathed-on M20s. Even a turbo M20 shouldn't worry a standard crank shaft. It's only a "common" problem because of the mental Icelandic tuners that run the engine on liquid NoS and make them produce in excess of 1000bhp for a very short space of time.

Lmao, yeah I mean who would expect a standard part to break if you put it under 2,5 times the strain it was designed to take... rocket science...