Us Flowmaster guys...
their 5db lower than a straight pipe, so yes they are. & they still retain a very deep sound.
Technical Article Contributor
Joined: May 2006
Posts: 4,391
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From: High Plains of West Texas
let the SLP revolution begin!! 
I got the idea from weazel who had a single LM1 I believe.. I just ran with it a bit more 
I'm thinking of doing headers this winter to really raise the db's!
I got the idea from weazel who had a single LM1 I believe.. I just ran with it a bit more I'm thinking of doing headers this winter to really raise the db's!
Last edited by FX4life; Oct 22, 2009 at 10:48 PM.
Just joking 
Senior Member
Joined: Nov 2008
Posts: 511
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From: Schenectady, NY
Muffler Flow Testing
All tests via an independent lab
All tests @ 15” wc
2 “ Straight Pipe 283 CFM
2 ¼ “ Straight Pipe 365 CFM
2 ½ “ Straight Pipe 521 CFM
2 ¼” Typical Bent tailpipe 268 CFM
2 ½” Typical Bent Tailpipe 417 CFM
2 ¼” Inlet/Outlet_ Glass Pack Tips- No Louvers- Smooth 274 CFM
2 ¼” Inlet/Outlet- Glass Pack Tips-Louvered 133 CFM
Same as above set for reverse flow 141 CFM
2 ¼” Cherry Bomb 239 CFM
2 ½” Cherry Bomb 294 CFM
2 ½” Inlet/Outlet Dynomax Super Turbo 278 CFM
2 ½” Inlet/Outlet Ultraflow Bullet 512 CFM
2 ½” Inlet/Outlet Gibson Superflow 267 CFM
2 ½” Inlet/Outlet Flowmaster ( 2 Chamber) 249 CFM
2 ½” Inlet Outlet Flowmaster ( 3 Chamber) 229 CFM
2 ¼” Inlet/Outlet Thrush CVX 260 CFM
2 ½” Inlet/Outlet Maremount Cherry Bomb 298 CFM
2 ½” Inlet/Outlet Hooker Aero Chamber 324 CFM
2 ½” Inlet/Outlet Hooker Max Flow 521 CFM
2 ½” Inlet/Outlet Borla Turbo 373 CFM
2 1/2" Inlet/Outlet Magnaflow 284 CFM
Standard OEM 2 ¼” Inlet/Outlet 138-152 CFM
Standard OEM 2 ½” Inlet/Outlet 161-197 CFM
All tests via an independent lab
All tests @ 15” wc
2 “ Straight Pipe 283 CFM
2 ¼ “ Straight Pipe 365 CFM
2 ½ “ Straight Pipe 521 CFM
2 ¼” Typical Bent tailpipe 268 CFM
2 ½” Typical Bent Tailpipe 417 CFM
2 ¼” Inlet/Outlet_ Glass Pack Tips- No Louvers- Smooth 274 CFM
2 ¼” Inlet/Outlet- Glass Pack Tips-Louvered 133 CFM
Same as above set for reverse flow 141 CFM
2 ¼” Cherry Bomb 239 CFM
2 ½” Cherry Bomb 294 CFM
2 ½” Inlet/Outlet Dynomax Super Turbo 278 CFM
2 ½” Inlet/Outlet Ultraflow Bullet 512 CFM
2 ½” Inlet/Outlet Gibson Superflow 267 CFM
2 ½” Inlet/Outlet Flowmaster ( 2 Chamber) 249 CFM
2 ½” Inlet Outlet Flowmaster ( 3 Chamber) 229 CFM
2 ¼” Inlet/Outlet Thrush CVX 260 CFM
2 ½” Inlet/Outlet Maremount Cherry Bomb 298 CFM
2 ½” Inlet/Outlet Hooker Aero Chamber 324 CFM
2 ½” Inlet/Outlet Hooker Max Flow 521 CFM
2 ½” Inlet/Outlet Borla Turbo 373 CFM
2 1/2" Inlet/Outlet Magnaflow 284 CFM
Standard OEM 2 ¼” Inlet/Outlet 138-152 CFM
Standard OEM 2 ½” Inlet/Outlet 161-197 CFM
Junior Member
Joined: Jun 2010
Posts: 4
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How Bout this 5.4 with a Flow 40
Just an "off the shelf" Universal offset single 2.5 in/out Flowmaster 40 Series 69.99 at A&A Auto.... I Love it!
Cold Start
http://www.youtube.com/watch?v=KHtpDqa8nu8
Donuts
http://www.youtube.com/watch?v=x2giWht2hhI
You can really hear it Belch at 0:12
Cold Start
http://www.youtube.com/watch?v=KHtpDqa8nu8
Donuts
http://www.youtube.com/watch?v=x2giWht2hhI
You can really hear it Belch at 0:12
