Hey, I've noticed with the new slightly more expensive tiers there is the item mentioned in the title added, which wasn't mentioned in the updates news. I assume I will have to upgrade to this tier to get this item? (So from the 25 to the 28)

Thanks, I'm super excited for this game.

Every kickstarter backer who pledges at least for one copy of the game (starts at $25) will get the trunks in the game later.

Actually, it's from $10, although you need to pay for the game later. Some people seem to be misunderstanding. Read the description of $25 tier at this page. Simply, $25 tier is an early bird edition. So, I'd say, grab the $25 tier since there difference is just the price - reward is the same. This is due to the restriction of the Kickstarter site which prevents existing reward tiers from being edited by the creators (This is why I recommended you to read the official site).