Simply stated, an engine is just a glorified air pump, and the power it churns out is directly related to how much atmosphere is sucked in through the intake and how much is evacuated out the tailpipes. It's also important to remember that it's a system, and both the "in" and "out" need to work in harmony so an engine can make its peak power. Choke down on the air coming in, and power will suffer. Conversely, a restrictive exhaust system will cause excessive backpressure and a loss of power.
That's where we were with our 2001 Z28 project car, Black Betty. A year ago we swapped in a cammed LS3, and while it did provide a healthy dose of added power, the car needed even more to keep up with the competition. After crunching the numbers, we began to get curious about how much the exhaust system was hurting us at the track. We had a set of JBA shorty headers in place, but even though they were better than the stock manifolds there was only so much they could do. The stock "crushed" Y-pipe and high-mileage cats didn't help either. To see what a free-flowing exhaust truly brings to the power table, we picked up a pair of Doug's long-tube headers along with their 3-inch Y-pipe kit. And since we were under the car we picked up a GMMG chambered exhaust system from Hawks Third Gen, partly because it flows so well, but also because it sounds killer.
1. We had been running JBA shorty headers, but even if you have stock manifolds, the first step is to remove the existing exhaust parts. The driver-side just dropped out, but we had to pull the starter to get the passenger-side header out.
2. As you can see, there's a big difference between the JBA shorty and the Doug's long-tube header, and all that dyno-tuned length equates to more power. The Doug's headers (PN D3340) have a street price around $750, give or take a $100. The ceramic-coated, stainless headers feature 1 7⁄8-inch tubes with 3-inch collectors. They accommodate O2 sensors and air injection.
3. It was a tight fit, but with the starter removed, the passenger-side header did slide in from the bottom. We were really impressed with the fit and finish of the pipes. The tubes are CNC mandrel-bent and the flanges were extra thick, which will help prevent any leaks.03
4. The driver-side header fought us a bit. Once we removed the oil filter, we were able to get it in place.
5. As far as long-tubes are concerned, we found that these didn't kill our ground clearance. They tucked up nicely to the Camaro's floor.
6. With the headers installed, it was time to address the Y-pipe. Due to the funky topography of the fourth-gen's floor, the factory pipe is flattened quite a bit on the left side. That, combined with the small-diameter pipe, doesn't help in the power department.
7. The aluminized-steel Y-pipe from Doug's (PN D900) is guaranteed to flow better due to its 3-inch diameter. Street price is just over $200.
8. We installed the first section of Y-pipe and loosely band-clamped it to the header. By leaving it loose, we were able to rotate the pipe to get the proper fit and floor clearance.
9. The rest of the Y-pipe fit with no drama. For added clearance, the pipe had been “flat-spotted” and those notches lined up perfectly with the floor.
10. The Doug's Y-pipe used the same mount off of the transmission as the stock Y-pipe.
11. The Doug's headers came with adapter kickdowns in case you want to run the stock Y-pipe with the long-tubes. Obviously we didn't need them.
12. We were amped when we found out that Hawks Third Gen was now selling the GMMG chambered exhaust system (PN HTCHAMB, $750). Constructed from T-304 stainless steel, these dyno-tested tubes have a bitchin sound that we fell in love with the first time we heard it. The system mounts using the factory hangers on 1998- 02 Camaros and will also fit 1982- 97 models.
13. Next, we installed the stainless intermediate pipe that came with the Hawks Third Gen exhaust system. The Doug's Y-pipe was kicked down to mate to the factory Y-pipe, so we did need to do some cutting and welding to mate the I-pipe to the Y-pipe, but it was worth the extra effort.
14. Aside from the tips, the Hawks system consisted of just two parts; the I-pipe and the chambered exhaust assembly. With the I-pipe installed, we slid the chambered section in place and popped the pipe over the axle, clamping it to the I-pipe.
15. Once the system was in place, we installed the slash-cut polished stainless exhaust tips that came with the Hawks system.
16. As we said, the Hawks chambered exhaust system is designed to fit 1982- 02 F-bodies as long as you use the 1998- 02 hangers.
17. The Doug's headers included O2 extension harnesses. These allow the forward O2 sensors to be moved back to the collector on the long-tubes.
18. With the cats gone, we didn't need to run the rear O2 sensors. This did cause a Check Engine Light to illuminate on the dash, but our plan is to have the ECU wizards at Westech Performance fix it with their laptop.
19. The new system looked great, we still had decent ground clearance, and the Camaro finally sounds the way it should. We also found that even though it was louder at idle and at full throttle, it was pretty tame on the highway when cruising in Sixth gear with zero drone in the cabin.
20. Westech Performance was able to program out the Check Engine Light and optimize the tune for the increased airflow.
21. After a few pulls, we nailed down a best pull of 448 hp and 445 lb-ft of torque. Compared to our previous best pull of 404 horsepower and 413 lb-ft, that's a huge gain and one that was felt across the entire pull.