Someone I know/57 E-code has 2 1/2-inch pipes. He had no issues with running the pipes through the frame; however, I don't know how they exit. 

I will have 2 1/4-inch mandrel-bent 304 stainless exhaust done by Bob's Muffler in Bakersfield, CA. Unlike most shops, they have the machines to do it. The cost of having them formed by hand is prohibitive, and I lack the skills to do it. 

Ok black-tie here goes, to do 3' pipes I had to enlarge the hole in the bumper-guard inserts as well as enlarge the holes behind the guards through the body. At the time I did this I couldn't find anyone to do 3" mandrel pipes so I bought a lot of 3" pipes and elbows ($500 worth) and cut and fit then welded them together and returned what I didn't use. I have the FPT headers and to get the 3" pipes through the frame in front of the mufflers I had to enlarge the oval holes. I have the Flowmaster Laminar Flow Mufflers (which are too loud) and no crossover or resonators. It was a lot tougher to get over the rear axle housing with 3" versus the 2" I had replaced. FYI I used the stainless band muffler clamps. I would think you will have a lot easier time with 2 1/2" pipes. Good luck!

  Vic Correnti

Tbirddragracer. Thanks. That's the info I was looking for. I was sure that 2" would work and possibly that 2 1/4" might work but didn't think that 2 1/2' would work. that would be ideal for what I want to do. What mufflers are you running? Are you running an H pipe and if so where? The frame really is in the way. 

Vic, did you have to remove the bumper-guard inserts to make room for those 3-inch tailpipes? I intend to run 2 1/4-inch mufflers and mandrel-bent pipes in the original location, coming off Sanderson headers, on my 55 Tbird. I have Borla Pro XS mufflers, and will include Borla resonators towards the rear, before tailpipes. Do you have an H or X-pipe? If so, what diameter? Got photos? Thanks.

My '57 has 2 1/2" stainless steel in the original location back to the adapter that goes thru the bumper.
Ernie

The 57 is an oval hole in the bumper rather than round like the 55. With the larger pipe you would have to flatten the end of the pipe. 

Joe is right except mine is a 55, my mufflers and pipe routing is in the original location. I'm not familiar with the 57 exhaust pipe routing compared to the 55. I know the bumper exit should be a lot easier then the 55.

  Vic Correnti

I am not absolutely sure, but I believe Vic Correnti has 3" exhaust pipes out his bumpers.   I am sure he will chime in if I am wrong.  Joe-JDC

JDC

Anyone know  what the largest tailpipe you can get through the bumper? Stock is 1 1/2". I am thinking 2" would be max. Also looking for performance mufflers. Currently running stock mufflers and tailpipes without resonators and like the sound. Problem is my engine with Mummert heads and Isky cam and Blue Thunder intake is around 400 horsepower. Looking to get over 400 with good headers. Running antique Hedman headers. Just ordered FPP headers. 4 month lead time. Need better system behind them. Looking at 2 1/2 in and 2 1/2 out mufflers. Trying to figure out what to do from the muffler back. Would like to keep exhaust through the bumper if possible. Thinking 2" would be max. Will this be a problem. Could go to 2 1/2" and dump it behind the mufflers or in front of the bumper. Not thrilled with either options. Looking for muffler suggestions and a tailpipe solution. Will install an H pipe and cutouts for the eventual drag strip runs. I want it to sound good but not so loud as to be obnoxious and annoying.