My PB for the regular 20 km route was 2 hr 2 min (which I thought could never be broken). Today it was 1 hr 59 min (including stops). After a longish 7 min wait, Hoo C C and myself proceeded to do my customary additional 8 km (I don't do an extra 10 km or 20 km OK, just 8 km).
My PB for the 28 km (with stops) was 3 hr 8 min. This time I did 2 hr 58 min. At IM China, Hoo CC outran me by a good 2.5 hours. Now we are about the same.
As Simon says, the key is to reduce one's weight to improve performance. I suppose the SKINS suit has passed its test with flying colours. Don't tell anyone I mistakenly wore it inside out.