when i first installed my header, i had it on a stock 6 system. It didn't change the exhaust note much but you could hear a little ping ping ping from under the hood. Not too much though with the stock cam and all. Then I got the super turbo and 2.25" exhaust and It was much better. Then I added the comp 260 cam and then the pings from the header started to get louder. It sounds great!
Later,
Paul