2nd on 5K race ... But it was very sweet placement

2nd place can be a bit bitter, but today for me was all sweet: the winner is by far too superior to everybody and I come home with a huge PB on the distance and great indication of shape for the marathon.
Let's go in order...
Today was the final race of the 5K series and the only flat 5K in HK.
The course is on a pedestrian road not closed for the race and full of twist, so not exactly a super fat course (last year I was hitting a pooing dog....).
Honestly, I was not very motivated to race because I hate running in the afternoon, it was hot (27C/80F) and I do not want to affect the training for the marathon.
I went only because being the last race of the series I wanted to collect the "goodies" and prize for the series and at the same time it is unrepeatable occasion for a 5k PB.
All said, I felt good on the warm-up and decided to use a passive tactic to follow the pack of runner at my level and just kick for the final km.
It all went to plan. After the start, the winner (congratulation Stefano for the fantastic time) disappeared fastand we formed a pack with my usual opponents (all guys capable to run below 16min in ideal conditions).
I just hang out there, covering every move and trying to avoid overstriding. The first 2k were tough because I was not used to these paces, but progressevely I felt better and I was not even at 100% effort. Felt very confortable, waiting for the right moment. With 1500m to go, I felt that the others were hurting and I placed my move, easily gaining ground.
With 500m, no one was closing by, so I cruised in good form to the finish line in 15'51".
A great PB, also considering the weather and the twisting course. I was not even hanging out for death, so there are other seconds to collect here and there...
As remark, the Italian domination in HK continues... Whenever we took the start line, either myself or Stefano win. Also today a 1-2 like last time ....

What would you do after a PB and before a marathon ????
Well, obvioulsy putting the time in the McMillan calculator or Jack Daniels' VDOT, right ??
They both comes out with a marathon equivalence around 2h32-34', and I also played a bit factoring the hot weather (2sec/km), the twisting course, etc on a time in ideal conditions.... But it could become really a wild dream...
All said, for sure I have the right aerobic power and stamina, I feel good general endurance, but lacking of something in specific endurance (marathon pace for long distance).
The answer in 3 weeks...
(I can not give a displeasure to Jack Daniels and McMillan...)