Help, my exhaust is killing me.

I'm going to pull the plugs tomorrow and see what they look like, no time today.
Today I was also told to advance the timing so the 'burn' was hotter, and that the size of the jets should have no bearing on the issue I am having.

More info and opinions are helpful, but it soon leads to confusion.

What everyone agrees on is that it runs very well as is, but I feel it could run better.

I'll follow up tomorrow, hopefully with good news.