I have Sanderson headers with 2 1/8 inch piping and Flowmasters mounted behind the rear axle and out the back on my 57. I didn't have them routed through the bumper to avoid problems of corrosion and burning of the chrome finish. Sounds great. I had Magnaflows at first but way to loud for me. Changed to Flowmasters and it is better. With the aluminum heads, cam, etc. the engine is louder over all and definitely has the characteristic Y block sound.

57 Black Tbird 312/auto

If you look at the piping diagrams for the birds, on some there is a resonator positioned aft of the x-member - inclined upward to cross over the axle. Cars without the resonators simply have a section of pipe in this position.

This stripped frame shows the location well enough....

It only takes a little imagination to move the mufflers out from under your seat and place shorter cans in the resonator position. The forward pipes can be insulated with header wrap if nothing else - and the wall behind the seat can be nicely deadened and insulated. 

Several who visit here have done this modification......

 
 Steve Metzger       Tucson, Arizona

Forgot to say that this application also eliminated or loosened up the fit issue of mufflers within the x-frame and gave my some room to play with options. Flowmaster has several inlet, outlet possition and size option. Personally I think 2" is adequate for 300-375 HP apps. But you will definitely have to modify where it exits thru the bumper even if its an 1/8 over. Hard to believe my originals were 1 7/8ths. Sounds tiny.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

Tried to respond yesterday but site locked up on me.



On my 55 I used flowmasters and I recall 2" or 2 1/8" tubing? The muffler shop didn't want to go any bigger. I chose to try mounting the mufflers out of the x frame altogether. They are mounted in what would be the "resonators" position on a 56 or 57 bird. This eliminated my heated floor problem. Flowmasters may be louder or more metallic sounding BUT it was hard to compare on my setup since I had changed so much on my engine and headers from nearly stock. I like it. I highly recommend investigating moving your mufflers back. Only issue one might come up with is they don't get rid of the condensation as easily but I think that is a small point. Also kept the pipes coming thru the bumperettes. The headers are FTP and you are going to get increase in metallic sound with these too. Again, It works for me.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

Do you have a part # for the Dynomax? How do they compare with Flowmasters and other performance mufflers as for as power output and noise levels? I want to run the tailpipes through the bumper. I need to take a close look at the adapter that goes through  the bumper and see if there is room to modify it for a 2 1/2 inch tailpipe.

2 1/2" will fit through the frame holes and there is a 2 1/2 Dynomax muffler that will fit in the X member. Behind the axle sort of depends on what you want to do. On my '55 I did not take it through the bumperettes but just ran straight to under the bumper. My bumperettes have '57 scrub front rubber bumpers which fit perfectly look better and don't get your trousers dirty if you brush against them. (What is good for the face of a scrub is good for the ass of a bird )

I also considered 2 1/2 glass packs but they were more restrictive than the Dynomax.



BTW I also put some thin gage galvanized on top of the frame over the mufflers. It is easy with a frame off but might be difficult with things together. This is to makes an air gap of cooler air under the body. It vastly reduces the heat through the floor which can be a problem with T birds.

Doug T

The Highlands, Louisville, Ky.

Planing the exhaust system for when I finaly get the car back together. Planing on using the headers that Mummert has listed on his sight unless someone has a better idea. How big can I go with tailpipes and still run them through the bumpers?