That's was my first thought also, but after hearing the video, Im suspecting mufflers. What brand/type are on there? I went thru 3 sets of Walker 17749's years ago, I couldn't figure out WTF was popping, sounded like friggin' popcorn in the tail pipes, then I noticed the tail pipes were being lined with fiberglass from the mufflers.
No, the stock converter is way better than what you can buy off the shelf. You can get better performance out of the motor, have your cake and eat it too, but only if you have a converter purpose built for your car. You have to pay for that though. If you wanted to do that, this is what I would buy. http://v8buick.com/index.php?threads/tsp-9-5-street-strip-converters-lifetime-warrantee.147066/
Sorry, I was thinking of the thread with the big cam. Stock converter is ok for your application. Didn’t mean to confuse you.