Back on topic - one of my favourite low cost upgrades is Nordost Pulsar points. Worked fantastically with my B&W 850 sub and going to try them on the HTM2D centre, this weekend.

G98, HD621, 568.25, 558.2, 559, B&W 803Ds, HTM2D, 4xSCM1, ASW850, Pioneer PDLX5090 50" Plasma, Cables by Atlas and Chord