Did you know that not all '57 Chevys are the same? Let me explain, lest you think I just fell off the turnip truck. According to the install sheet on our Flowmaster instructions, the platform for the '57 Chevy was available in two different versions and from six different plants around the U.S. and Canada ... eh. That would make quite a few '57s that are slightly different from one to the next.
Now it's 50 years later and those '57s may have (and probably should have) had altered suspensions, height changes, big-block swaps, etc., thus furthering the mutation effect of the chassis. Imagine trying to engineer a one-size-fits-all exhaust system for this type of platform. Imagine no more. Flowmaster has recently hit the market with a complete "one-size-fits-all" '57 Chevy exhaust system called American Thunder.
For all the rubber-neckers out there, here's a shot of the 2 1/2-inch U-Fit Dual Kit, with the Super 40 Series muffler.
Jason Scudellari (our Primedia Tech Center guru) does quite a bit of wrenching for many magazine titles, so we asked him just how good this Flowmaster "bolt-on" system was. He responded, "I was very pleased at how it went in. Only a couple of minor issues came up."
Jason informed us that he had to bridge the gap between the header collectors and the start of the exhaust with a lead-in pipe. That's to be expected owing to the varied amount of header manufacturers and header lengths on the market.
That's pretty good news for those who have a stock-styled '57. But what about the guy who has power-packed his '57 with a 572 big-block or an LS-based engine? Or the person who has an aftermarket IFS rear or front clip under his '57? Lions and tigers and bears, oh my, where do the variations end? Flowmaster has an affordable answer for that problem too. Known simply as the U-Fit Dual kit, this universal system will conquer the unknown exhaust issues that an altered vehicle may present. We'll spend most of this article following the install of the U-Fit Dual kit, since it's the more difficult of the two to tackle.
This particular kit does not come with exhaust hangers or mounting hardware. They can be ordered separately from Flowmaster. | 
These headers were used on both '57 Chevys. Doug's Headers has an established history of making high quality headers that not only increase horsepower, but look good, too. The Tri-Y headers (as they are called) are ceramic coated and designed to fit most Tri-Five Bel Airs. | 
After installing the Tri-Y headers, the lead pipe from the collector had to be modified in order to fit the exhaust as tightly as it needed to be. |
The first half of the install from the collectors to the mufflers is the easier part of the job. The cut pipe is butt-joined and tacked into place. The welds will be finished a bit later. | 
The exhaust pipes are tucked in tight against the body of the vehicle and don't hang below the frame. There's nothing worse than seeing an exhaust system that hangs too low. As the pipes are being fit and welded, Jason makes sure that they are always level and propped into place. | 
Just after the transmission (right about where the crossmember is) is a good location to place the H-pipe. This too will have to be measured, cut and welded into place. |