A company called Broader Performance has been doing some independant flow testing, they have a web site and gues what.....it seems the ol glasspacks (the good ones) actually outflow the 2 chamber flowmasters. The best one they have tested is Hooker MaxFlows....

Check it and all that spent their money for the sound...good for you, all those that spent their money for the "performance", i feel real bad for you!

 

I can attest to this. I've had a Flowmaster 50-series SI/DO. Initially just replacing it with a glasspack SI/DO netted a hp increase by the seat-of-the-pants meter. Changed that out for a true dual system w/Magnaflow cats and glasspacks with an x-pipe and haven't looked back since.

-Flea

 

Straight-through mufflers have high flow. Some are rated at over 2000cfms. Not everyone prefers the "ol glasspack's" sound, the rotting out of mild steel, or the fiberglass that blows out. There are similar design race mufflers that sound better, are made of stainless-steel, and have superior packing.

 

Maybe why one of our local Flowmaster Dealer/Installer recommended Glasspacks over his Flowmasters!!