The kind of oversideboarding @diophan is talking about is really common in vintage (probably in magic). If you can get a handle on that you'll be ahead of the curve. Just make sure you follow it to it's natural conclusion. If you don't have enough cards in your deck to take out in order to fit, say, the Echoing Truth ... then that Echoing Truth could have been something more useful in another matchup. Adding cards to a sideboard without considering what you need to cut for them is a critical error I see people make all the time.
Congrats man. I'm glad to see you enjoyed the list. I worked on that thing quite a bit, and although I've had some low points with the deck, I've had some amazing runs with it as well.
Lotus Petal seems so innocuous, but it gives you 8 zero cmc artifacts to power out a quick oath, and it fixes, and it's great with yawgmoth's will. Also it can help you play dig through time in a pinch.
Good luck with it in the future!
@xouman I didn't consider dropping some Drains. In my first tournament, my list was a bit different. It was with main deck Tinker-Colossus, and the black tutor package instead of red.
My feelings with the present list are goods. But sometimes Drains is not castable in the first or even second turn, so I will probably go down to 3 copy (or may be 2). Also double red Spellbomb isn't needed.
The draw engine was very good, Dack is just awesome to filters, while Jace control opponent draw. But again, I'm far from an Bomberman expert or experienced vintage player, so don't take me on words ;)