I have a GSA-4082B and suffer from coasters when using low quality discs but only when writing more then 3.5GB and then the end of the disc is unreadable.

I thought maybe if I try to write at a lower speed then the 4X the discs are made for it might work, but I can’t make any burning program write any slower.
I tried Nero 6, CloneDVD and Alcohol 120% and all of them write at 4X.
I have the original A201 firmware.

Any help will be appreciated since there is a very large price difference between the discs.