Oh yeah - brake upgrades. If 320mm fronts with R4 pads don't cut the mustard at warp speed, your next reasonable options are:

1) Movit's 380mm Brembo setup ($if you have to ask, you can't afford it)

2) StopTech's very sweet 355mm kit (~$2500)

3) OE Brembo 334mm R129 brakes ($1000-$1500 total)


I have a set of the 334mm brakes that I was thinking of putting on my E500, but honestly the stock 320mm's worked better than I thought they would, and I may just leave them alone. I might be persuaded to sell them if the price was right. Total weight is the same as stock 320's since the caliper is aluminum, and the brake pad is larger too (more swept area). Heck, I might even let the 300mm rears go too, if I'm not gonna upgrade the fronts...!