This is a double posting, you know this is against the rules here
What firmware version is installed on your drive? Make sure, you have latest official firmware from Sony. Unfortunately, sonyisstorage.com has reorganized their website, so I couln't find the last version there, but maybe there are other sources for that.
Burn quality depends on the media you feed your drive with, no firmware can turn crap into gold. Also, I doubt, that the reading performance was improved with newer firmwares, Liteon firmware included.
so successfully will flashing the firmware to a LITE ON one as said by Codeking and others in the above posts. will show some better performance and better burns ?
It depends, see above.
also what are the + points of flashing it to the LITE ON .firmware. ??is it worth taking the risk ..?
At least you will void your warranty. The advantage of Liteon firmware is support for jitter scanning with Nero CD/DVD Speed and Online Hypertuning that can be enabled with the test version of SmartBurn Utility.
also can i revert back to original firmware if anything goes wrong ?
You can crossflash your DW-Q120A to Liteon SHW-160P6S and vice versa. You need patched firmware, that you can find in the firmware thread here.