Poll on are you running Stock or Modified engines

Modified in a performance way, I said basically stock cause most cars aren't 100 % stock anymore so if you a holley instead of factory carb but everything is stock then I would say basically stock, even say you got 340 and use a similar cam even if slightly better I'd say stock.
Generally if you replace parts for performance gain then modified if you use some performance parts as replacement for general repair i'd say basically stock.
I agree with that generally. If you replaced a 600cfm Carter with a 600cfm Holley you are still in stock.

If you replace the stock cam with one "slightly better".. IMHO.. no longer stock. As you say.. performance gain.

I don't consider headers an engine upgrade even with the sometimes massive gains you get over the stock logs. Wonder if I'm alone there.