Installing a 3-inch Flowmaster Exhaust After we bolted the Lester Scruggs 404ci engine into our Orange Peel '66 Chevelle using Edelbrock motor mounts and headers, it became obvious that the leftover 21/2-inch exhaust system was due for an upgrade with a Flowmaster American Thunder 3-inch exhaust system. Since Lester makes a serious 560 hp, a 3-inch system seemed an ideal choice. We plan to put miles on this Chevelle, and 3-inch systems are notorious for their bellicose exhaust notes. Normally, the Flowmaster American Thunder kit is shipped with a pair of 40-series mufflers, so we opted instead for a pair of larger (and yes, heavier) 70-series Big-Block II pieces with a pipe kit (PN 1033). The Big-Block II mufflers are 9 inches longer than the 40s, so squeezing them under the car was going to be a challenge. We decided that Kevin McMillan at McMillan Speed and Fab has far more talent than we do, so we took the Chevelle to his shop and spent a day massaging the pipes. An exhaust system may not be very romantic, but when installed correctly, it will enhance not only the sound but the fun of driving. Our 3-inch system is rock solid, virtually disappears under the car, and sounds fantastic. It doesn't get much better than that. DESCRIPTION PN SOURCE PRICE Stainless V-band clamps, 3-inch Call McMillan Speed & Fab $65.00 Flowmaster 3-inch system 17202 Summit Racing 615.95 Flowmaster 70-series mufflers 53073 Summit Racing 271.90 Flowmaster pipe kit 1033 Summit Racing 528.95 Refer to text below. We decided a pair of Steve Watt Enterprises stainless V-band clamps would be perfect at the junction between the mufflers and tailpipes. McMillan welded the late-model-style Flowmaster hangers to the tailpipes to support the system. By removing four bolts at the header flanges and two small V-band clamp nuts, the entire centersection of the exhaust system can be quickly dropped out of the car. We decided a pair of Steve Watt Enterprises stainless V-band clamps would be perfect at th The key to any exhaust system installation is to tuck the mufflers and pipes as close to the floor as possible for ground clearance and aesthetic reasons. McMillan accomplished this by placing the mufflers in their best location, spot-welding them to the floor (with clearance), and building the system around the them. The key to any exhaust system installation is to tuck the mufflers and pipes as close to t A. McMillan added O2 sensor bungs aft of the Edelbrock header flanges on both sides so we could keep track of the air/fuel ratio. B. The Edelbrock LS engine swap headers offer a straight shot from the collectors to the large 70-series mufflers but sacrifice ground clearance. We found a set of Hooker LS swap headers that fit much tighter to the floor, producing an additional 2 inches of ground clearance that now need to go in the car. C. If this system is hard to see in the photo, it's because McMillan painted the entire system flat black to make it blend in easier with the underside of the car. It's amazing how a small step like this makes the installation more professional. D. McMillan fashioned small L-shaped brackets that use a shock absorber polyurethane isolator to locate the tailpipe without noise. The entire system is ridiculously rigid with zero rattles. E. The original Flowmaster system exits just behind the rear tire, but we decided the tailpipes needed to exit farther back to look correct. McMillan used an 11-inch section of pipe removed from the lead-down pipes near the headers to extend the tailpipes. SOURCES Flowmaster Inc. 100 Stony Point Road Suite 125 Santa Rosa CA 95401 800-544-4761 www.flowmastermufflers.com Steve Watt Enterprises Ventura CA 805-798-09 www.maxwellindustries.com McMillan Speed & Fab Oxnard CA 805-278-3900 www.speedandfab.com By Jeff Smith Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!