Porsche 0-60 Times & Porsche Quarter Mile Times | Porsche 911 Carrera 0-60, 944 Turbo, GT2, Boxster S, Cayman R, GT3 and Porsche Cayenne 0 to 60 stats!
The above site posts 0-60 and 1/4 mile times for various cars, apparently based upon averages from contemporary magazine tests. They show the following:
1999 Boxster 2.5: 0-60 6.3 seconds, 1/4 mile 14.8 seconds
2000 Boxster 2.7: 0-60 6.0 seconds, 1/4 mile 14.5 seconds
http://www.howstuffworks.com/porsche-boxster-history4.htm
The following is a quote from the above web page in connection with 0-60 times:
"Porsche pegged the 2000 base Boxster at 6.4 seconds in the benchmark 0-60 dash, a modest .3 seconds up on the 2.5 litre original. The real-world time was probably more like 5.9...."
The actual times vary, although it would seem clear that the difference in 0-60 times is at least .3 seconds as between the 2000 2.7 and the 1999 2.5. I don't have my brochures here with me (and I don't have one for a 2001 Base which was a bit heavier than the 2000 due to the lined top and cupholders), but the 6.5 second figure you refer to may reflect 0-100 kph (which is actually a little over 62 MPH), or it may have increased slightly due to the additional weight.
Brad