Porsche 997 Turbo manual vs BMW M5 E60 with chip and exhaust (http://www.dpccars.com/car-videos-09/01-19-09page-Porsche-997-Turbo-manual-BMW-M5-E60-chip-exhaust.htm) pretty close race at first but the Porsche starts pulling at top end.

I'm kind of surprised by that video cause M6's which weigh the same as the M5 with a tune and a exhaust can take down Z06's. And there are a few video's of Z06's beating porshe turbo's stock vs stock.