I've been to SIN a dozen times so I should know the answer to this question. But here's my situation:

Arriving on a Garuda flight at T3 at 9am. Then connecting to an Air India Express flight from T1 departing at 10:45am. They're 2 different tickets, and I won't have checked in luggage. Given the terminal change, I'm pretty sure I have to go through immigration, take a shuttle to the new terminal, check in, go through security check, etc. While AI Express doesn't have a great on-time reputation, this particular flight seems to always leave on time since the inbound flight arrives before 6am, giving it ample buffer.

If I'm not mistaken I've done similar transfers before in a similar amount of time. But I thought I'd check to see what the collective wisdom is. Is 1:45 too tight to make it?