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New C4 Exhaust System - More Bark With Your Bite, Part 1

New C4 Exhaust System Adds Power And PRRRRR

Dick Moritz Sep 1, 2008
Corp_0809_01_z New_c4_exhaust_system Header_system 2/30

Here's our header system from Stainless Works, complete with A.I.R. plumbing, an EGR port, and a bung for the O2 sensor, along with nifty band-type clamps that are attractive, effective, and don't crimp the pipes being clamped, making any future disassembly a hassle-free experience.

You know how some things you do on your Corvette are quick and easy? Like bolting on a performance air cleaner, adding graphics decals, or laying in a set of custom floor mats? These are things that take little time and, usually, not a lot of bucks, plus add an air of distinction and maybe a modest boost to performance or handling.

Well, this story is about installing a complete performance exhaust system on an '87, and frankly, it is none of the above. It's not quick, it's not easy, and it's not inexpensive. In fact, it's a real pain in the butt to do. But if you've got the budget, a little creativity, and lots of patience, it's well worth the trouble.

Corp_0809_02_z New_c4_exhaust_system Rear_half 3/30

Removal of the rear half of the original exhaust system is as simple as removing three bolts at the flange of the catalytic converter and two hangers at the rear of the mufflers. It all comes down in one piece, which we'll keep for the lucky guy who will end up restoring this car twenty or thirty years from now. Before removing the cat converter, we marked the underside of the car at the rear edge of the catalytic converter flange. This would allow us to be sure the new system was in the proper fore-and-aft position to ensure proper alignment and positioning.

Here's the deal: we sought out the best combination of exhaust system parts we could find-street performance headers from Stainless Works with their beautiful thermal coat finish and a high-performance catalytic converter from the folks at Random Technologies, who know a lot more about performance tuning than we ever suspected. For the cat-back pieces, we asked for advice from the tech people at Mid America Motorworks, who recommended a Corsa muffler package that they felt gives the best blend of sound and substance for our somewhat-modified C4.

Removing the factory exhaust system was straightforward, even though it was twenty years old. The real challenge was fitting the headers in amongst all the parts that attach to, or pass near, or are in the way of them. And we don't fault the header design for that. Stainless Works has done a masterful job of designing equal-length headers to fit in a space where most folks would say headers would never fit. And they've constructed them to accept all the factory emissions system pieces in order to keep the Feds happy.

There are an awful lot of heat shields, brackets, and other parts in the vicinity of the headers, and they all must be dealt with in a limited working area. We did the job on a lift, and it's fair to say that this job would be virtually impossible without one. By our estimate, with no exaggeration, we probably raised and lowered the lift at least fifty times in the course of doing this job, finding things in the way, moving or modifying them as we went, until we were able to get the headers bolted into place. Once the headers were mated up to the cylinder heads, the rest of the job was pretty straightforward.

Corp_0809_03_z New_c4_exhaust_system Air_feed_tube 4/30

The air feed tube to the catalytic converter is a multipiece affair. We used a cut-off wheel to surgically remove the clamp, being careful not to nick the tubing since we knew we'd be re-using it with the new system.

Along the way, we had to fabricate a couple of brackets, bend a few tubes (not the header tubes, obviously), add a couple of spacers, and trim a number of heat shields to make everything fit. We even had to fabricate a special tool to tighten two of the spark plugs that were inaccessible once the headers were bolted up. in the interest of appearance, since our Project '87 is a Show 'n Go car, before we started the installation we sent the cat-back pipes to the artists at Classic Coatings, whose chrome-like finish was nothing short of breathtaking.

OK, so the job was a huge hassle. Was it worth the time, trouble, and expense? We think so. The finished job is just gorgeous, rattle-free, and provides an exhaust tone that's just perfect-a pleasant burble at idle, a proper growl when you're hard on it, and virtually as quiet as the factory system during cruise. We don't know how they were able to make the system work this way, but we're sure glad they did.

Since C4s span many model years, there's no way to show every step for every year. But we will share with you the highlights and lowlights of the installation on our '87, cautioning, as they say, "Your results may vary."

Because getting the headers up into place was, by far, the most time-consuming part of this job, we've divided the story into two parts. This first installment will cover removal of the stock exhaust and installing the left-side header; next time we'll cover the more involved task of installing the right-side header and the remainder of the new system.

Corp_0809_07_z New_c4_exhaust_system Left_side_exhaust_manifold 8/30

The left-side exhaust manifold lifted out easily without the need to remove the alternator, just the bracket mentioned previously. We were even able to leave the spark plug wires installed while removing the left-side manifold, but we did have to remove them and the spark plugs, on both sides of the engine, in order to position the new headers.

Corp_0809_08_z New_c4_exhaust_system Catalytic_converter 9/30

The high-performance catalytic converter from Random Technologies is more than just another replacement converter. In our discussions with the folks at Random, we were impressed with the depth of their knowledge in overall engine management and how it must be carefully integrated with various performance parts so everything works in harmony.

Parts ListStainless WorksC48591 '85-'91 Corvette headers plus Y-pipe/ThermalcoatNBC250 (4) accuseal high torque band clampEBC250 (2) accuseal wide high torque band clampRandom Technology191-30001 high-performance catalytic converter w/accy'sMid America Motorworks628-096 Corsa exhaust system cat-back603-930 catalytic converter hose kit614-559 (2) muffler insulatorsLocal speed shopARP header bolt kitHeader gasket setLocal Chevy dealerDipstick tube

Tools Of The TradeIn addition to everyday hand tools, such as screwdrivers, wrenches, and sockets, you'll also need:5/16-inch, 12-point, 1/4-inch drive socket for header bolts1/4-inch open end or box wrench for hose clamps for A.I.R. hoseTorx T-20 socketCut-off wheelImprovised spark plug wrench


Random Technology
Loganville, GA 30052
Stainless Works
Chargrin Falls, OH 44023
Mid America Motorworks
Effingham, IL
Classic Coatings
Sheboygan, WI



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