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.