I had a Spintech Pro Street 6000 series on a V6 and I loved it. It did drone around 2500 RPM's though, but I lived with it. Even with a small V6 people heard me coming, but I didn't consider it loud at all.
I've been tempted to run the 6000 series on my 360 but I fear they might be too loud on twice as many cubic inches, full length headers and no catalytic converters to boot.
