Great post 12 o'clock.
Pick up 10 hp by switching t6 to t5 pipes? First I've heard. My bike ran awesome with t6 pipes and they do good with porting.
Shears are of course a good drag pipe. IMO it's not how much power a set of pipes make. What's important to me is where it makes power and how. But I'm going off topic here so I'll stop
As for stock carbs, they are fine. You can stroke it and run tons of compression and they will work great. IMO leave them along till later down the line. And money you spend on stock carb mods can be used to pick up a set if 28pwk or 30oko. If you go too big of a carb u can sacrifice bottom end.
If you decide to get your bike ported down the line, ask the builder what he suggest. They can help you the most.