There’s endless chatter about exhaust systems and what performs and sounds the best—with headers, mufflers, and pipe sizing being the prime discussion topics. The system you choose determines the sound and performance once everything is buttoned up.

Seems everyone has their favorite muffler. For my money, Flowmaster has always delivered a nice throaty bark (though all exhaust system manufacturers deliver their own unique sound with a lot of bang for the buck). It is all in the sound and performance you are personally seeking from an exhaust system.

We’re working with a Flowmaster American Thunder Series complete exhaust system including long-tube ceramic-coated headers to keep heat inside and rust from forming on the outside. Nice thing about header technology today is ball and socket collectors that make light work of header disconnection when you want to open them up.

Any time you’re installing an aftermarket exhaust system, you’re bound to run into challenges calling for modifications such as bellhousing clearance, or chassis and floor pan issues.

Take it all in stride and make your modifications clean and tasteful.  

man welding exhaust tubing under a car
You’re going to need a wire-feed MIG welder, which can be rented for a one-time use. Summit Racing also offers a variety of affordable home-use MIG welders that run on household current. All you have to do is learn how to weld beforehand—which takes practice. A good exhaust shop can also handle the welding. (Image/Jim Smart)
fitting exhaust headers into engine bay of a classic car
Header installation is remarkably easy, especially in a mid-sized GM car like a Chevelle, Olds 442, Buick GS, or Pontiac GTO. (Image/Jim Smart)
fitting exhaust headers under engine bay of a classic car
The right-hand side header installs from the top; the left-hand side from underneath. (Image/Jim Smart)
bolting up a set of headers to a v8 chevy engine
Order up a set of locking ARP header bolts or Stage 8 locking header fasteners, which are a foolproof locking system. (Image/Jim Smart)
inserting header gaskets
Install the two end bolts first as a gasket guide, then install the header gaskets. Watch out for any debris that might be on the gaskets and flanges. (Image/Jim Smart)
a set of headers exiting under a classic muscle car
These long-tube Flowmaster headers align perfectly with the Chevelle’s undercarriage. Whether you have a Chevy, Pontiac, Olds, or Buick—count on a precision fit. (Image/Jim Smart)
jacking up an exhaust section under a classic muscle car
The Flowmaster H-pipe is a perfect fit. We’re using a transmission jack to support the H-pipe and get it into position to line up with the headers. We like the ball and socket collector system, which allows the headers and H-pipe to dovetail together. (Image/Jim Smart)
man welding an exhaust system under a classic car
Once everything is in perfect alignment and the receivers are bolted to the headers, the H-pipe ball and socket receivers are welded to the H-pipe. (Image/Jim Smart)
a pair of bare exhaust pipes under a vintage car
Flowmaster exhaust systems are mandrel bent for reduced turbulence. This is where the pipes slide into the American Thunder mufflers. (Image/Jim Smart)
man fitting a muffler into a classic car
We’re doing an initial fit between the H-pipe and mufflers before installing bolt-on ball and socket receivers, which will be used as quick disconnects for racing or muffler swaps. (Image/Jim Smart)
marking exhaust tubing sections prior to cutting
Measure twice, cut once—double check that everything clears the chassis and floor pan. (Image/Jim Smart)
cutting exhaust tubing with a saw
Make sure you’re cutting at the right location before picking up your saw. (Image/Jim Smart)
checking size of an exhaust flange prior to cutting
The owner wanted quick disconnect collectors at the mufflers for swaps and weekend racing. (Image/Jim Smart)
welding an exhaust flange onto tubing
The collectors are welded to the mufflers and pipes as shown here. (Image/Jim Smart)
a pair of flanges welded onto exhaust tubing
(Image/Jim Smart)
jacking up a muffler onto a car prior to welding
The Flowmaster American Thunder mufflers are secured. (Image/Jim Smart)
close up of an exhaust flange clamp
We like the quick disconnect feature employed here, which makes muffler swaps and removal simple and quick. (Image/Jim Smart)
fitting exhaust tips onto a classic muscle car
The last segment is the tailpipes and bologna-sliced tailpipes. What you want from these tailpipes is a very subtle look beneath the rear bumper. There are plenty of exhaust tips you can source to achieve any look desired. (Image/Jim Smart)
Keywords
chevelle, exhaust system, Flowmaster, headers, muffler
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Author: Jim Smart

Jim Smart is a veteran automotive journalist, technical editor, and historian with hundreds of how-to and feature articles to his credit. Jim's also an enthusiast, and has owned and restored many classic vehicles, including an impressive mix of vintage Ford Mustangs.