Stock Engine

I have a '91 LX with the 302 in it. I've had it almost a year now. I know that the headers are factory (because the spark plugs I replaced were). But, I was curious if anyone had any information on specifications of the factory headers. I'm doing a few mods here and there for performance upgrades. This was one area I was going to consider for improvements. Would this be a recommended improvement. I have a flowmaster exhaust already. Any help would be appreciated.

Thanks,
sb