I don't know what weird secret ways you could go about getting level 20, but I believe that you can make it to level 17 still.
Ok here's the deal.
You can gain XP from mobs until you are 6 levels above them. The highest-level mobs in PS are the Charr Bosses at level 10. So of course you can go to level 16 using them.
I have looked up the PS quest list on
Guildwiki so here is what you can get from quests. This is by area (W/o profession quests):
Ascalon City - 11 quests = 2900 XP
Lakeside County - 14 quests = 3750
The Catacombs - 1 quest = 250
Barradin's Estate - 1 quest = 750
Regent Valley - 1 quest = 250
So all up you can get 7900 without the profession quests
For the profession quests you need to play a mixture of warrior, monk, ranger, or necromancer. Mesmers and Elementalists have one less quest than the others, so it will not work if you choose one of them as one of your professions.
You then do the Test Quest for your primary profession for 500 XP. This gives you your basic primary skills.
You then do a New Trainer Quest and pick any secondary you wish to use for 250 XP.
Next you can do all six secondary profession quests for each profession. Simply choose whatever secondary profession you wish to keep for last and then make that one your permanent secondary. This will net you 1500 more XP.
If you chose some combination of Warrior/Ranger/Monk/Necromancer you will then have two more quests for your primary profession and two more quests for your secondary profession. This will give you an additional 1000 XP. If you chose Necromancer as one of your professions you will gain another 250 XP, as the quest The Accursed Path gives you 500 XP rather than 250 XP like all of the other extra profession quests.
So you have 7,900 XP without the profession quests.
The profession quests add another 3250 or 3500 XP with Necromancer.
So the total XP for Presearing quests is either 11,150 or 11,400 (with Necro).
According to this chart -
Chart 1 - It takes 11,000 XP to get from level 16 to level 17.
So as you can see, you have a 150-400 XP buffer to get level 17.
Now the problem with this is that you can not even do the first quest to get your primary profession's basic skills, as this quest gives you 500 XP and you can't get the skills until you complete the quest.
You can't even take the quests from other trainers who normally give you skills to use before you complete the quest, as you have to complete your primary profession's first quest before you can take theirs.
So if you want to reach level 17 you have to grind to level 14 killing only mobs and having absolutely no skills to use or additional attribute points. Then from level 14 to 16 you would have to keep entering the Northern Territory to kill the few level 10 Charr bosses they have, each time having to be in a group or at least having someone open the gate for you each time you need to rezone to respawn the few bosses they have.
Once you grind to level 16 from that, only then would you be able to start taking quests and finally get your skills and attribute points as you work your way to 17.
So yes I believe it is possible for you to do this, but if you do then you probably don't have a life...
Please feel free to check my math and tell me if something doesn't add up right with the different quests and XP levels.
Livingston