Junpei, your problems are probably caused by the media you are using :
From all evidence this appears to be fake Taiyo Yuden media.
This comes in two types, one is pink or orange and the other is white and black.
The pink and orange ones seem to be made by Prodisc and people have reported problems problems burning on these with the 4163B. Yes, that's right - LG discs that won't burn properly on an LG burner. Some people have no problems with them, others have problems with these. Quality seems to vary from batch to batch.
The black and white ones seem to be made by Daxon and have a Sony MID (at least the 8x +R ones anyway). These are quite good and burn quite nicely on a 4163B. I have used about 15 of these with no problems at all.
Over the last few months of going through these forums, I have mostly only heard complaints about these discs (+R or -R, can't remember exactly which). I have also talked to someone who has used Samsung's DVD-RW discs on a Samsung DVD recorder and had lots of problems with them. Samsung media not working on a Samsung device. His problems went away when he switched to another brand of discs.
Here is a long list of media (DVD+R and DVD-R) that I have used with my 4163B that has worked for me :
a. Verbatim Datalifeplus 8x DVD+R pearl top MID : MCC003
b. Verbatim 5 Color Collection 4x DVD+R MID : YUDENT00-T02, sometimes YUDENT00-T01
c. TDK 8x DVD+R MID : CMCMAGE01
d. TDK 8x DVD+R MID : RICOHJPNR02
e. Ricoh 16x DVD+R MID : RICOHJPNR03
f. Fujifilm 8x DVD+R (Made in Japan) MID : YUDENT00-T02
f. Fujifilm 8x DVD-R (Made in Japan) MID : TYG02
g. Sony 16X DVD+R (Made in Japan) MID : SONYD21
h. LG black and white 8x DVD+R MID : SONYD11
i. Imation I-Crystal 8x DVD+R MID : CMCMAGE01
Just in case you think only good quality media works on this drive, here are some poor quality discs I have tried that worked (but who knows how long the discs will last) :
a. "Pinky Stripe" Mitsubishi 8x DVD+R MID : MCC003 (the edges of these discs are rot off)
b. Melody 4x DVD+R MID : MEDIA-ID-001 (the edges of these discs rot off)
c. Emtec 4x DVD-R MID : VDSPBM001
Try and pick better quality media and it should give you much better results. The cheaper ones may be able to burn, but the discs may not last. Two of the three cheaper ones I've used have the edges of the discs rotting off after a few months.
As for how to tell if A105 works better, the only way is to burn discs before you flash to A105 and then burn the same type of discs with A105. The do quality scans on both and compare. Don't worry about this now. Just get your drive to burn properly first.