I just wanted to add; in young people, high blood pressure is often also related to a stressful lifestyle (including being afraid of your blood pressure :-)
You've done a great job reducing your blood pressure, and if you can reduce it down into the 120s, it would (in my country) be completely normal, rather than "high normal" that you have now (this is variable from country to country, in Norway, <120 is optimal, 120-130 is normal, 130-140 is high normal, in US, <120 is normal, and 120-140 is prehypertension. I don't know what the guidelines are in Australia though. But we can all agree that 150-160 is too high, especially for a 27 y/o man.
Live healthy, avoid excess salt as Jon said, exercise if you can, avoid smoking and too much alcohol. If you at some point need medications, it's not the end of the world :-) the alternative is worse.
Your BP is slightly elevated. You may be able to control it by avoiding processed foods and foods with a high volume of salt. Don't forget that soda had a huge amount of salt, try to avoid that as well. You can also ask your doctor about exercise as that will also lower your BP.
Good luck.
Jon