I made what I thought was a gearbox cover using some spare bits of that sound insulation material used for boats. Approx 1" thick, silver on one side with a heavy sheet of something sandwiched between two layers of foam.

Result?

1) it looked awful
2) it reduced the amount of space in which one could rest one's left foot
3) it didn't make a huge amount of difference.

Threw it away. I have found however that an old pair of oily overalls draped around the area has just as good an effect.