As hot rodders, there are few of us that can leave well enough alone. In spite of our promises of leaving our latest acquisition stock, eventually the urge becomes too much to bear. And, it's usually only a short time later that the UPS guy is at the front door with boxes full of parts.
LS1 guys are no different. Now that these cars are being paid off and coming off of warranty, more and more people are getting the itch to up the "oomph." Curious as to what the average Joe could expect from a well rounded upgrade package, we decided to contact SLP Performance Parts to see what they had to offer. They fixed us up with a more aggressive cam, complete header and exhaust system, and an improved intake manifold from the new LS6/ZO-6 combination.
So, cool! We had a car, we had some parts, now all we needed was an install-and-testing facility. We needed to look no further than Doug Rippie Motorsports (DRM), just outside of Minneapolis. DRM specializes in late-model Corvettes but has tons of experience on F-Bodies as well, which is no surprise since they share the same engines!
Doug Rippie Motorsports' claim to fame is the ability to tune a combination to its maximum, a skill that you will see them clearly demonstrate here. Consider that you can buy an affordable all-aluminum LS1 engine from GM Peformance Parts (or SLP, for that matter) with EFI on board, as well as coil-on-plug ignition and a set of the best cylinder heads Detroit has ever had on a production line, and you'll see that this tech story goes beyond GM enthusiasts. This is an engine for everybody!
We think the results are pretty impressive, especially considering that this car is totally tame to idle around town in. You could take your mom on a cross-country road trip in this thing. So follow along as we walk you through the "gotchas" that come up during a complete exhaust install this month, while taking on a cam, spring, and intake swap next month. It's a bolt-on bonanza!
Removal of the stock exhaust system (up to the catalytic converter) can be accomplished the easy way or the hard way. The easy way is to break out the blue-tipped wrench or a Sawzall and cut the tubing right in front of the rear axle. If you wish to save the system from the ravages of a torch and power tools, the upper and lower panhard bars must be partially removed in order to snake the system over the rear. Since we figured there is no way the stock system would ever be re-installed, we elected to do it the easy way. | 
SLP's headers are the first full-length examples made with tuned tube lengths for LS1-powered F-Bodies. The length of each header tube was calculated to maximize scavenging, which translates to faster revs and increased torque and horsepower. SLP's headers utilize 1 3/4-inch stainless steel primary tubes with a 3-inch stainless steel collector and a high-luster thermal coating. The headers utilize OE-style and quality flanges and are completely compatible with EGR, the oxygen sensors, and the air-pump systems. SLP offers installation kits complete with all gaskets, bolts, fire sleeves, clamps, and brackets that are required for your specific application. | 
The factory Y-pipe is removed next, followed by the catalytic converters and the stock exhaust manifolds. Check out the flattened section on that stock Y-pipe--we imagine GM's biggest concern here was with ground clearance. |
Instead of jumping right into the installation of the headers, our man spent 10 minutes chasing the threads in the O2 bungs and EGR fittings. While this is not strictly necessary, it can save you from some later aggravation. | 
The driver-side header slipped into place with minimal fuss, but we had to get creative with the passenger side. The trick was to disconnect the transmission mount from the crossmember, which allowed us to lift and pry the trans to one side. It still took a bit of coaxing, but once we had everything lined up just right, it slid in pretty easily. Don't get impatient here--it really does fit! | 
We missed a small problem during the install. Occasionally, during hard acceleration, the Y-pipe would meet the stamped crossmember shown here. We went back and shimmed the crossmember with a few washers to gain the necessary clearance. Save yourself some hassle by checking this carefully the first time! |
With the new gaskets installed and the headers bolted up, it was time to concern ourselves with wire harness routing. The general rule of thumb is that you want at least a 1/2-inch air gap between any wiring and exhaust components. Route the wires carefully, ensuring you have sufficient clearance, and tie-wrap them in place. A few extra minutes spent here will save you untold hours of grief later if you should melt a harness. | 
Next on our install list was the 3-inch stainless steel Y-pipe and optional high-flow catalytic converters. As you would expect, the Y-pipe has been designed to work specifically with the SLP headers, and therefore, fit perfectly. And though a flattened section like the stocker had does not choke this Y-pipe, ground clearance is more than adequate, even on lowered cars. | 
The SLP Dual/Dual after-cat system is not as aggressive (read: downright obnoxious) as the newer Loudmouth system, but it does offer a refined, muscular sound without invoking the wrath of your neighbors. As with the Y-pipe, it is fabricated entirely of stainless steel and is a direct bolt-on replacement for the stock system. |
With the exhaust install complete, it was to the dyno room where we were rewarded with a jump in power to 322 hp and 339 lb-ft at the rear wheels. That's an increase of 18 hp and 16 lb-ft from where we started (more like 22 hp and 19 lb-ft at the flywheel). Some people trade for the next year's model to get a gain like that! Next month, we'll finish the project by installing SLP's cam, spring, and LS6 intake package. Should be good. |  | |