You can reach 200 without using Nitrons or perks, just by using the thrust pack. You can't get over around 240 without however - but I find you'll seldom catch up with someone going that fast from a standing start either.
Edit: Been looking at the ranks since it's taking ages to get through gold, the curve is really wierd:
It takes approximately:
6000XP to get to 5
40,000XP to get to 10 (silver)
230,000XP to get to 20
420,000 to get to 25 (gold)
685,000 to get to 30
995,000 to get to 35 (platinum)
1,350,000 to get to 40
1,770,000 to get to 45 (obsidian)
2,250,000 to get to 50
Silver -> Gold takes 11 times longer than Bronze -> Silver.
Gold -> Platinum takes 2.5 times longer than Silver-> Gold.
Platinum->Obsidian takes 1.8 times longer than Gold -> Platinum.
Obsidian -> 50 takes 1.3 times longer than Platinum -> Obsidian.
The sharpest increase in the amount of XP required to get to the next level is actually between levels 23 (32,000) and 24 (37,000), where this is an increase of 15%. 49 (2,150,000) and 50 (2,250,000) is only an increase of 4.5%. You need to literally earn the same amount of XP again to get from 25 to 35 (100% increase), but only half as much again to get from 35 to 45 (50% increase).