dennyW..I did ask for pros and cons based on the product. Not a personal attack. The sound, is what I wanted not the performance gain or loss..I don't think I have to worry about knock sensors or anything like that. I have a 69 350 4 bolt main in a 1947 ford COE with a Marmon Herrington 4 wheel drive and a stock Ford 4 speed tranny with the granny gears......talk about slow. So the irony in looking for performance...I have to laugh..