Any upgrades for the SFL-2 Preamp?

I own a SFL-2 Preamp which was bought used. Eventhough everything is great with it, I wondered if there are any upgrades offered by Sonic Frontiers since it was produced...I do not mean different type of tubes but parts upgrades. Furthermore, are there any dramatic changes that have been experienced with different types of tweeks or cables? Any input is appreciated.
Check with Sonic Frontiers I heard that the SE upgrades for the Line series can be applied to the SFL-2. Also do a search on audio You will find posts about this on the tube site.
Upgrade to a SF Line 3 preamp and you will not be disappointed. I upgraded from a SFL-2 also, and without any question Line 3 is a major step up in sound quality compared to the SFL-2. More refined and neutral.