Sorry for the belated update due to work related travels.
I got the car back from the dealer. The good news is, I finally managed to upgrade some mods such as predator programmer, FFRP muffler, ken bell pulley and retune..the car now dyno at abt 620rwhp. I LOVE the FGT even more!!!
Regarding the fuel filler neck issue, the problem seems to be solved now. But the dealer told me that since my car was previously being modified for the GTB doors, the dealer said that apparently when the door modification was being done, the installer had somehow damaged the fuel filler neck pipe. Therefore, they said they have to refabricate it and some modification is needed. So, I had been told that it is not under warranty in which it costed me around CAD1700 for the job.
Just felt abit sad to suffer this fuel filler neck issue but was not being covered under warranty...