Ask 100 people what a strut brace across the top of the towers on a MacPherson-strut frontended car does and 99 of them will tell you itís the stop the towers caving into the engine bay when the going gets tough. But theyíre (largely) wrong.
Nope, the strut brace is there to stop the towers pulling out, away from the engine. Think about the forces when you turn, say, hard left at speed: The left front tyre wants to tuck under the car, pulling to top of the strut tower out and away from the car in the process. Thatís why strut braces can look skinny but still work;