I went to Car & Coffee in Irvine with my friend and next door neighbor who has a 335i 6mt putting down 410whp. He has a full Brembo GT BBK, custom tuned, front mount intercooler, intakes, full 3" catless exhaust, and coilovers. I was really surprised that my Z with just Stillen sway bars and some exhaust work was able to keep up in the turns because his tail was getting happy while I was just tracking perfectly through the turns matching his speed. On the straights, he annihilated me but no as bad as I initially would have thought.
The big weight is the achilles heel of those cars, but there is no denying how well rounded they are.