Maybe the Philips firmware is better than the Liteon version.
Regardless of firmware, these drives don’t go lower than 16x for CD-R.
The “slowest” CD-writers I am aware of are Pioneer and Renesas based LGs, which start at 4x (and even this might no longer valid for the most recent models).
Apart from that, there is no need for that low burning speeds. The drives often don’t work well here, and also the media is optimised for higher speeds.
And: Liteon drives are not among those I would recommend if CD burning matters…