Super Saiyan said:
Only thing is, Goku still seemed quite afraid of his power level when he arrived on Namek (iirc), and he could use some pretty high Kaiokens at that point.
Goku could already match or even surpass 1st form Freeza with kaioken x4.
There are only two explanations for Goku being afraid on arrival that I can think of. One is that Freeza can't lower his BP properly so Goku could still feel the ki of Freeza's body (540,000) even if he Freeza wasn't putting it into his attacks against Nail.
The other is that he was afraid because he just knew Freeza was strong and didn't know his intentions with regards to Gohan, Krillin, Bulma, the Nameks, the Dragon Balls and the planet itself.