this is pretty funny, I use to have 99 Z28 6 speed, no mach1 or cobra (stock) was even close. Stock for stock the Ls1 is a much bigger engine and puts out around 300 to the wheels stock where as the machs and cobras put down around 265-275, not to mention the Fords are 200-300 lbs heavier, maybe more. My 98 M6 weighed in at 3370 with me in car. I have a Cobra now and love the Fords, but it is funny to log on and everyone and their dog has beaten an Ls1, yet in all the road tests the the ls1's were way faster than any of the Fords we are talking about.