Backfiring is getting worse

[Chris_H]

As far as the timing is concerned, I haven't touched it since Jan when we put the Novi in. Unless it has changed on its own, I don't see how this has become the problem, but I will check the timing anyway.
As far as the gas. We can only get 91 octane here, pretty pathetic I know. But I have gotten gas at the same station for the past 3 years. Unless they have had bad gas for the past month, then I don't see this as an issue either, but it's time for the octane boost anyway. I even got gas in Phx this weekend, and I still had the same issue.
I don't know if the exhaust leak could be the cause of this, but the leak has come in the past month, along with the more consistent backfiring. I know I need to get that fixed, its just a matter of time.
I will take off the mass air meter, mess with it a little, and try it again.

Thanks for the help
Chris