Yes, I think you are underpaid.

The harsh truth is that for the past 18 months or so, most of the Singaporean manufacturing sector have been looking upon new Malaysian applicants as people who want to leave Malaysia for socio-political reasons, and thus tend to low-ball.

The silver lining is that if you're OK with that and would like to tough it out, once you work diligently for about 2 years and prove your worth, you'll likely get the 'standard' Singaporean package.