This, if you are in the latter stages they will want to see everything you are saying is true. If you're projecting a hockey stick growth, but don't necessarily have the numbers to back it up that's ok, projecting is just guessing in any business. None of the good VC's I've done business with would be put off by this. If you've overinflated your numbers 20%,then it's time to have a heart to heart with your champion at the VC firm. If they are senior enough to get the deal done and they believe in you/your team, it may not matter. VC's invest in people as much if not more than a company.
No matter what happens be honest with these people, the VC community is small/close knit and if this goes bad because you weren't honest from the get-go EVERYONE will know.