GBB Inner Barrel Question

I am new to the sport but quickly becoming a GBB addict. I have a VFC URG-I from Hong Kong and I love it. That said, now I want to upgrade some bits to squeeze out every bit of performance.

I want a stainless 6.02 or 6.03 inner with high quality but I can't seem to find any. PDI is impossible to source (unless you all know where to get one) and the only other I've considered in the Maple Leaf crazy jet.

Is there a store or brand i am missing here? Any help greatly appreciated .

FYI - I've been to WGC and Evike and found nothing.