I don't understand why owners ditch the original airbox. I always hear about how hard it is to get the boot to seal, but a little Ultra Black RTV takes care of that issue. It's not rocket surgery.
IMO, those filters are a bit small. I used to recommend an oval K&N, but they're getting hard to find and increasingly expensive. Now, I use Uni Filter foam pods attached to the original "velocity stacks". It looks like someone has cut yours down, better than none I guess.
Jets don't come in "sets", you'll need to purchase them individually. You really shouldn't need to change it much, if any. Usually just raising the needle one notch is all that's necessary in my experience.