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How To Install a Catback on a 2003 Honda Civic EP3

Honda’s hatchback offering for the new millenium was the EP3, the three door hatchback that first introduced the aftermarket to the wonder that is the K20A2. While many experts and automotive pundits loved the stiffer chassis and refined looks, many aftermarket enthusiasts had mixed results when faced a Civic that was far from the standard that Honda had set.

The K series engine found in this car was truly bleeding edge and something that redefined what the aftermarket could achieve with a particular platform. And while many would argue that the older B series motor is still more cost efficient, there is no doubting the technology and ambition that is the K20A.

Today we’ll be bolting on a BLOX exhaust catback part number BXEX-20105, which has unfortunately been discontinued by BLOX Racing. Many other alternatives exist for those wanting an exhaust catback, and installation procedure remains mostly unchanged no matter what you have.

This makes our How To Install a Catback on a EP3 a good choice for learning how to upgrade the Civic’s exhaust.

Today we’ll be installing this catback on a 2003 Honda Civic Si EP3, and putting it on our dyno to see what our gains are before and after.

Tools you will need to complete this job:

 

Secure and raise the vehicle up on jackstands or using an automotive lift, make sure to use jackstands and operate on a flat surface. As with all of our writeups, if you do not feel comfortable working on your own car, take your vehicle to a certified ASE mechanic.

This guide is intended to show you how to install a catback without the hassle of taking it to a shop. So only perform this job if you are comfortable with your ability to get it done.

Here is a look at the stock catback exhaust system for a Honda Civic Si EP3, as you can see these bolts look pretty rusted and can potentially strip. As the bolts and nuts are susceptible to stripping and therefore making the reinstallation difficult, we recommend using a penetrating oil or spray like Blast Away to soften the rust.

 

After allowing the oil to soak through your nuts and bolts, gently use your 14mm wrench to crack open the nuts making sure not to strip any of the bolts.

 

With these 3 nuts loose, now turn your attention to the back half of your catback right after your fuel tank. This catback section is next on our How To Install a Catback guide.

 

Take your 14mm wrench and undo the spring loaded bolts that secure your axle-back section to the midpipe of your exhaust.

 

After loosening these 2 bolts, now remove them completely which should allow you to remove your rear axle back.

 

You might want to take this time and unbox your exhaust, and lay it out in front of you to ensure you have all the hardware needed for install. Now remove the 3 rusty bolts that come directly off the header pipe and catalytic converter, and have a friend help you remove the midpipe by sliding off the exhaust hangers.

 

Now with your full stock exhaust removed, now begin the install of your replacement exhaust by bolting on the new midpipe to your catalytic converter.

 

Move your exhaust hangers from your old exhaust and slide them onto your new catback. Now with the midpipe lined up and secured via your exhaust hangers, now snug up the 3 bolts to your catalytic converter.

Hang your axle back in the back of your EP3, and use the rear hangers to loosely hang the axle back in place before lining it up to your midpipe.

 

With your new catback hanging from the exhaust hangers, now line up your axle back and midpipe and snug the bolts but do not tighten. You may want to ask a friend to help you as you shift and adjust the placement of your exhaust canister before tightening all of your bolts.

 

Once you have your catback all lined up, you can now tighten down all the bolts and nuts and you have completed this How To Install a Catback job! Congratulations!

Happy Driving!

 

 

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