I am running the all welded Thrush $29.00 version of the Flow Master 40. 2.25" pipe all the way to the bumper and turned down. The sound is very mellow on up through 2500 rpm. That is 60 mph for me with the 2.76 gears.
After 2500 it will get louder which helps me to keep the speed in check. My commutes are 130 miles a day. I get a slight drone at 30 mph, 1 mph above or below it's gone, other than that it is great! I like the sound with the engine advanced allot. It has a nice peppy on step feel and sound.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Aggressive Ted,

Do you have headers or sock manifold? Im thing about the 2.25 or 2.5 exhaust with the same muffler, stock manifold. Do you have a vid? I would like to hear it!

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

Running the stock manifold for now. It has been ported up top and down at the bottom to match the exhaust pipe. It takes a fair amount of time to port it out but well worth the effort. It makes a noticeable improvement in power and in mileage.

Some one posted a clip of a blue Dart Sport of Duster with dual FlowMaster 40's. Mine sounds very close to that. Very crisp sound at idle on up through 2500 rpm, then roars when you open it up.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG