This is an aftermarket catback exhaust swap on a 1996 mazda miata as shown to the left. All exhaust swaps will be similar with only small differences. Reasons for an exhaust swap can be a leaking stock exhaust or maybe just to have an increase in horsepower. Another good reason to replace the stock exhaust with an aftermarket one is the material used in aftermarket catback exhausts. The material used is generally stainless steel which will never rust as a stock one will. Horsepower increases will vary depending on the stock systems flow and if the engine is turbocharged or naturally aspirated.
Do you live in an area where you car has to meet inspection requirements? Normally your vehicle will also have to pass emissions requirements also. This article will help explain what emissions are and how to fix a possible problem your vehicle may have. The emissions test is normally done with a probe placed into the exhaust tailpipe. The emission sampler will sniff or sample the contents of the exhaust coming out of the tailpipe. Every road going vehicle produced, has certain clean requirements that it is required to reach. This requirement is specified by EPA to limit the amount of pollutants exiting the vehicle. Most samplers are five gas analyzers simply meaning they “see” or measure five types of gases. The five gases that will be measured are HC, NOX, O2, CO, and CO2. We will start with HC or hydrocarbons. HC’s are simply another term for unburned fuel that makes it through the engine and out the exhaust. HC’s cause smog and and are not good to breath. NOX means oxides of Nitrogen. NOX is a by product of highly heated and compressed air that has nitrogen in it.
Rotary engines have the ability to make large power gains through tuning. One of the most important aspects of rotary tuning is rotary exhaust. Rotary engines produce very strong hot pulses of air. The strong exhaust pulses can be used in a manner similar to two stroke exhaust tuning. The exhaust can be tuned to scavenge the intake air into the engine causing a filling of air into the intake side. The intake air is trying to fill the vacuum of where the exhaust has left. Racing headers from companies like racing beat and mazdaspeed can bring large improvements in power. Muffler and larger tubing mandrel bent exhausts can also largely improve the power of a rotary engine. Rotary exhausts should not be cheap normal exhausts. The increased temperatures and pressures of the rotary exhaust will quickly break or destroy a normal exhaust. The preferred exhaust systems will be larger gauge (thicker) and best made of stainless steel. Even the mufflers are made thicker and welded better. Horsepower gains will vary on regular and turbocharged cars but will be substantial on both types of vehicles. Some rotaries may experience over 10% power increases! This is the first place to look for performance in a rotary powered vehicle.