Buckin' Bronco

Take any 14-year-old truck and chances are the exhaust has seen better days. Such was the case for this '90 Bronco 4x4, but we didn't just want to replace the stock system, so we opted to improve it with a more efficient and powerful system. That's where Flowmaster comes in. Combining some online research with the experience of listening to Flowmaster-equipped vehicles in person, we decided that an after-cat system would be the perfect addition for this Bronco.

Flowmaster, founded in 1983, has just about dominated the racing market and, with its distinctive sound and proven reliability, seems to be the muffler of choice for hot-rodded street cars. After studying the Flowmaster website (www.flowmastermufflers.com), the decision to select the Force II system, which is designed for '87-'96 Ford Broncos with 5.0L and 5.8L engines, was pretty easy. This kit included heavy-duty 0.075-inch-thick walls, aluminized pipes, and a Flowmaster muffler. It also includes all of the clamps, hangers, and brackets needed for the job. The aluminized pipes will add durability to the system, and since we didn't plan on babying this rig, that's a good thing.

One benefit of ordering a complete system from Flowmaster is that everything is included and the pipes are mandrel-bent for a perfect fit and the best performance possible. Flowmaster says its system outperforms most OE and competitive aftermarket systems because every Flowmaster system is designed and tested for each specific application. Even the length of the tailpipe is considered because this can be an aid in keeping atmospheric pressure from rushing back into the muffler. Tailpipes can improve performance and control sound when they are designed correctly. As a rule, Flowmaster says tailpipes should be a minimum of 10 inches and no longer than 6 feet. If your tailpipe length has to be more than 6 feet, you may need to add a resonator. Thankfully, when you order a kit, it's all figured out for you.

The size of pipe used in an exhaust system is another critical item to consider. When you see import fans with their trash-can-sized exhaust systems, it seems like a somewhat logical conclusion that bigger is better. But, while pipe diameter will affect the sound level and performance characteristics of the muffler, it is important to understand that bigger is not always better. A pipe too large can actually hinder exhaust scavenging by allowing atmospheric pressure up the pipe. As a rule, most general street applications use 2- through 2.5-inch pipe, while modified street applications will generally use 2.5- or 3-inch-wide pipe.

The muffler, the heart of the system, may look simple when you see a drawing of the internals, but it has taken many years of intense research at Flowmaster to develop the patented technology that uses the pressure and sound energy released from an engine's combustion chamber into the exhaust system to create a low-pressure area between exhaust pulses. Flowmaster's designs use this energy to scavenge, or pull spent gases out of the cylinder. Flowmaster says it's even more efficient than an open-pipe system. And Flowmaster would know, as it has used track, highway, and dyno testing to prove its designs.

The bottom line is that the Flowmaster kit bolts right on with no fabrication required, it will last a long time, and the sound has just enough of an edge on it to make this Bronco sound more impressive than it is. Follow along as we install the Flowmaster kit on this '90 Bronco.