I borrowed a high end audio recorder from work last year when I was getting my longtubes put on so that we'd once and for all have an actual comparison between them instead of "longtubes will be quieter while cruising and louder at WOT."
Enjoy
BBK Longtube Headers vs OEM manifolds on my 1996 Cobra - YouTube
Enjoy
BBK Longtube Headers vs OEM manifolds on my 1996 Cobra - YouTube