Yup, after watching it again and reading a lot of comments in my opinion Pete P is in fact Soze but obviously Verbal was very clever to incorporate him into the story as Kobayashi the Lawyer. Why he needed to tell Kujan about Kobayashi at all I'm not sure. To make up a well rounded plausible story I guess.
I tend to think that Verbal wasn't just a Hitman but they were working together to create the Keyser Soze myth as they were both very clever crims.

Why would the movie be about someone not Soze himself fooling the police so brilliantly, and so how likely could such a character exist? The main job was a job for the man himself, not an underling. Kobayashi was whomever he was in "real life", a lawyer this time, perhaps an accountant next, but always only Soze's accomplice and sidekick.

Nothing is certain in this movie obviously so there's no "proof" of anything, but based on Kint's statements there's no reason to believe Kobayashi exists at all (let alone that he's a lawyer.) Sure someone picks Kint up at the end of the movie, and that is the same actor playing the person dramatizing Kint's statements to Kujan, but you have to assume everything Kint tells him is pure fabrication.
If you just look at what is "known" outside of Kint's statements, you realize that everything between the actual line-up in New York and the shooting of Keaton by Kint/Soze is based entirely on Kint's statements, which are shown to be unreliable at best. There's no reason to even trust that McManus, Fenster or Hockney were in LA at all, or even saw them after they were released from the holding cell (everything we know about what occurred in the cell is based on Kint's testimony to the prosecutors in LA.). The robbery of the police obviously happened (Kujan knows of it; it would have been a national story given its scope) but there's no reason to believe "the usual suspects" we're involved in anyway.
Keaton's whole personality as described by Kint is totally at odds with the killer described by Kujan. Kujan's depiction is far more reliable.
Soze as a myth obviously is known. I'd say on the evidence presented in the movie that Kint is him, but what his business was with the other criminal, Keaton, nothing is ever said for certain

Well I don't think there is a Soze. I think that he is just something that Verbal and Kobayashi cooked up as an alias behind their operations. So in that sense I think they are both Soze and neither of them are. I think it makes sense that a con man and a lawyer could have created this elaborate lie about a criminal mastermind.
It's all theory though which is the beauty of the film that I think those who thought the twist was predictable done understand: it still leaves so much open to interpretation making the film infinitely re watchable

Verbal is Soze, no question of that, and there's no question that a person named Keyser Soze exists.

I don't think so - Soze wouldn't be driving the car personally, and Verbal wouldn't keep Soze waiting while he lit up a cigarette the way he did. Going by the body language, Verbal is the senior of the two, but it doesn't mean to say that either of them is Soze.

I personally don't think he is. It makes more sense if Verbal's behind the Soze myth, since he's such a fantastical liar. I think the appearance of the lawyer at the end suggests that there's some truth to Verbal's story. But your interpretation is possible, the director and actors have basically said it's up to the viewer to decide.