the facelift in 99 increased power from 340-360bhp

the 0-60 for the 340 is 6.6 but ive got a magazine which has the 360 at 5.6 secs

can 20 bhp make that much difference

also, the advert just says 99 how do i know if it is the 360 version ? its got sat nav which is a sign it may be