[Laguna454s3]

I recently saw a documentary about High Speed trains (Europe and Asia) and one segment was about tunnel design. Anyhow, as a High Speed train enters a tunnel it creates a pressure wave in front of the train that when it exits creates a Shock Wave that is very loud.

To reduce the sound of the exiting Shock Wave by 30% the exit of the tunnel is elongated and the opening is angled.

I figure that the same theory could apply to exhaust exiting a tailpipe. If you cut the ends on a 45 deg rather than at 90 deg it may give a similar effect. Additionally, if you angle the tailpipes downward the sound should reflect off the ground making it somewhat quieter.

John

[AdamIsAdam]

Well, I don't know about that, but I can tell you that I have a 2.5" exhaust, with X pipe and Flowmaster 40's exiting out of 2" tail pipes. It's not too loud at all, but sounds pretty nice outside. See a quick video here:

http://www.youtube.com/watch?v=5UEYR-ApA7k

These mufflers were free to me because my friend's GTO also with stock manifolds and 2.5" exhaust with H pipe had them on and it was WAY too loud for him. Plus, my car is a ragtop so I'm more concerned about sound than he is!