heezy545i

I doubt your car is much slower than before, but heavier wheels and tires can only hurt performance. There is some debate to how much unsprung weight actually affects things, but more weight can't help.

Here's a decent article on acceleration with heavy versus light wheels. The delta in times and speeds weren't really that great. http://www.carcraft.com/projectbuild/116_9...ison/index.html

Even though the difference may not be that great, it still makes a difference. If you remember back to the runs we did, which seems like a lifetime ago, hollywoodtrash's 550i was about even or perhaps even slower than your 545i or mine from a roll. At the time, we agreed that his 20" wheels made the difference. However, when hollywoodtrash tested his launch control with the g-meter, his 0-60 was faster than any of ours, so go figure. 0-60 and 1/4 mile times are all about the launch, so perhaps your launch and shifts were better than before.

As for improved handling, well weight again is the enemy. Larger wheels could improve handling if it allowed you to fit wider tires, but I believe your tires are the same width as when you had your 19s. Or 10mm wider in the rear if you had 275s. A lower profile tire can help with response, but there is a limit with things.