You have to quiet down your car with a minimal loss of power...

[rogue]

Originally Posted by clill

The sound meter at Laguna is on the right side of the track. Make tailpipes that you can add 90 degree turns on the ends to point the exhaust to the left. Pozzi runs there and should also have tips. Sometimes even your engine makes it too loud and you might need a closed air cleaner and underhood insulation.

I was reading about the elbow tricks. I've also read that people shift into high gear before the booth and cruise by

[David Pozzi]

Here's a more complete version of what you posted:

MUFFLER SHOOTOUT:

Results based on 5.0 Mustang Magazine December 2002 issue (page 55). Test car is a ’90 Coupe with 370 HP and 11 second potential. A number of 66 pulls were made to compile this information. Where does your muffler stack up?

The results in HP order:

1.Flowtech Warlock (open) 374.2 hp/ 333.1 tq
2.Bassani Real Street 373.7 hp/ 333.8 tq
3.Hooker Maxflow 373.5 hp/ 333 tq
4.Borla XS 373.3 hp/ 332.6 tq
5.Magnaflow 372.8 / 332.5 tq
6.MAC 372.3 hp / 331.5 tq
7.Flowtech Afterburner 372.3 hp/ 330.1 tq
8.Hooker Aerochamber 372.1 hp/ 330.4 tq
9.Bassani 372 hp/ 333.5 tq
10.Spintech 371.6 hp/ 332.2 tq
11.Edelbrock Performer RPM 370.9 hp / 331.3 tq
12.Borla XR1 370 hp/ 334 tq
13.Flowtech Terminator 369.5 hp / 331.3 tq
14.Dynomax Ultra Flo 369.4 / 333.2 tq
15.Flowmaster 369.4 hp / 331.8 tq
16.Flowtech Warlock 366.3 hp / 325.3 tq
17.No muffs 365.2 hp / 330.1 tq

Sound Off in Quietest to Loudest (Decibels):

1.Borla XS, 80db at idle, 90db at 2,000 rpm, 110db at WOT.
2.Hooker Maxflow, 80db at idle, 90db at 2,000 rpm, 120db at WOT.
3.Magnaflow, 82db at idle, 91 at 2,000 rpm, 114db at WOT.
4.Flowmaster, 82db at idle, 93 at 2,000 rpm, 115db at WOT.
5.Flowtech Warlock, 83db at idle, 92 at 2,000 rpm, 112db at WOT.
6.Dynomax UltraFlo, 83db at idle, 94 at 2,000 rpm, 113db at WOT.
7.Borla XR1, 83db at idle, 96db at 2,000 rpm, 118db at WOT.
8.Bassani Street, 83db at idle, 96db at 2,000 rpm, 120db at WOT.
9.Edelbrock RPM, 84db at idle, 93db at 2,000 rpm, 118db at WOT.
10.Bassani Real Street, 84db at idle, 96db at 2,000 rpm, MAX. (120+db).
11.Flowtech Afterburner, 86db at idle, 94db at 2,000 rpm, 115db at WOT.
12.Flowtech Terminator, 86db at idle, 94db at 2,000 rpm, 119db at WOT.
13.Hooker Aerochamber, 87db at idle, 94db at 2,000 rpm, 114db at WOT.
14.SpinTech, 87db at idle, 97db at 2,000 rpm, 116db at WOT.
15.MAC, 87db at idle, 98db at 2,000 rpm, 119db at WOT.
16.No Muffler, 91db at idle, 103db at 2,000 rpm, MAX. (120+db).

Here's what we used:
Walker Dynomax 17733 2.5" in and out.
Dynatech stainless V Band clamps 2.5" Summit DTC-60-912250S

Here's a great "sound advice" page written by a friend of mine who does open track events for the Shelby Club at Laguna Seca.
http://www.norcal-saac.org/ot/soundadvice.htm

[Tom Fuehrer]

Originally Posted by clill

The sound meter at Laguna is on the right side of the track. Make tailpipes that you can add 90 degree turns on the ends to point the exhaust to the left. Pozzi runs there and should also have tips. Sometimes even your engine makes it too loud and you might need a closed air cleaner and underhood insulation.

Diddo on pointing the exhaust away from the meter.

When I raced my Mustang for the first time I registered a 118 db (100 feet from the track edge at BHF, driver's left). I was running a simple system with a dump in front of each back tire.

I rerouted the left side pipe to the right side and the reading dropped to 93db.

Sometimes it's not so much quieting the car as it is keeping sound pressure from the meter.

Tom