There are many things you can do to a CR-X.  To start off you can replace the stock intake & exhaust system.  I had a DC Sports ceramic coating headers installed, with a Trust stainless steel exhaust system.  Right away I can feel the increase of power on the top end.  The car runs smoother on the freeway.  One thing I have to point out is that Trust exhaust on a CR-X is not very loud.  So you might want to look into something else if you want it to be loud.  I ordered a battery mount kit from Summit Racing and relocated the battery to the trunk.  This free up some space under the hood and allowed more space for the intake system.  I installed a Hot Shot intake system made for Honda Civic.  The reason is they are shorter and looks better.  The after market intake system for CR-X has a very long tubing and has too many bends.  For the battery, I recommend the Optima Red Top battery.  One time I left my headlights on for 3 hours, came back and started the car.  A very good battery if you are running a killer stereo system.

To lower the car I replaced the springs with a set of Neuspeed Race springs and Tokico gas shocks.  The car handles great, but the ride was awful.  The ride is so bad that you can’t even play a CD, it will just keep skipping.  I also tried a set of Eibach Sportline springs.  It’s a lot better ride, and the car lowered just about the same.  I also replaced the stock wheels with a set of 16x7 wheels.  They fit just right and they will not rub.  If you are thinking getting 17s you will need to trim the inner fender a little.

For the stereo system, you can put just about anything in the back and it will sound good due to it’s hatchback design.  I tried adding a Bazooka base tubes, just have to make sure it’s facing a corner of the rear trunk for the best sound.  I tried switching to a bandpass box with two 10” Kicker.  The bass was mind blowing, but the only bad part is that you no longer will have a trunk.  Also, the rear trunk panels are very fragile on the CR-X, made of some kind of cheap fiberboard.  So when you removing those panels you might want to be careful.  For the highs, you can purchase a set of Q-Form kick panel enclosure.  You can purchase them from Crutchfield.com.  I highly recommended because it will give you a better sweet spot and you can mount a 1” tweeter and up to 6.5” mids by the kick panel.

If you are thinking adding some leather in the car, you can simply purchase the leather seats for the Acura Integra and they will just fit exactly without any modifications.