With the Nitrous Express System installed, it’s time to do the rest of the car, and one of the common modifications requested by customers is a muffler and exhaust system. Googling the term “ideal exhaust size” will give you 1,000,000 different results, none of which are actually helpful. Even in car specific forums, ask 10 different people, and you’ll get 10 different answers as to what is the best exhaust system.

Here’s the short and easy answer. Bring your car to us and we’ll figure out the math for you, because that’s our job. You don’t have to worry about the size, shape, etc etc., let us do the computation for you, and we’ll give you actual power figures and results, not just guesses or conjecture.

For this Eclipse, the instruction is to do a complete, and by complete we mean from the headers up to the muffler.


1. We choose a Greddy chambered muffler with a 2.5” inlet for several reasons:  Quiet at idle and low rpms, gives a low bass growl as you floor the throttle and the revs climb higher, looks pretty good with the rainbow tip, and the inlet is the correct size.


2. We do a test fit of the muffler to determine the position.


3. We then start fabrication of the piping using mandrel elbows as we TIG weld everything together. For the Eclipse, the ideal size happens to be a 2.5” piping which is the same actually as the stock piping size. Other cars will vary.


4. We custom make 2 sets of headers, one for the front and one for the rear, since it’s a V6. Note the integrated catalytic converter on the stock header, and the lack of it on the custom header.


5. A very important part when making headers is the correct placement of the factory O2 sensors. Most muffler shops often neglect this or put it in the wrong place, leading to all sorts of problems such as check engine lights or worse, lean conditions.


6. It’s not often you see only 3 pipes coming out of the front of the engine.


7. We put in a small 18” resonator to quiet down the initial flow of the gases.


8. Here’s the completed exhaust system up to the Greddy muffler.


9. Now that looks just nice and perfect.


10. Here’s the completed engine setup with the intake and the headers.


11. To complete the package, we also installed a Unichip to tune the engine for optimum efficiency and to control the Nitrous Express System as well.  The customer wanted big power and big power is what he got! In stock form, the Eclipse clocked in at 210whp. With the K&N intake, custom full exhaust and Unichip tuning, we got 264whp, a huge gain of 54whp! And with the Nitrous Express activated and spraying, we crossed the 300 mark and ended with 307whp total! More than enough to beat most any cars on the road, including Evos and STIs!