Since this project has been underway for some time– much work has already been done!  An overview:

• Modified airbox — I’m a big fan of ripping out any resonators in the path of the stock intake.  They’re only there for sound purposes, and who doesn’t like a nice, growling intake?  You almost always pick up a little throttle response as well.  I’ve never liked aftermarket intakes, and those cone cotton filters don’t filter nearly as well as OEM paper.  Even Team RTR used a modified airbox on their race-prepped Spec V!
• Energy Suspension Motor Mount Inserts –These are a popular modification to prevent wheel hop when launching the car.  They literally fit into the soft stock rubber mounts.  They’re made of polyurethane, and they insert into the lower mounts that are on the crossmember.  Installation wasn’t too big of a deal.  I’ve noticed increased throttle response, and almost zero wheel hop!
• Nismo Front Sway Bar — Originally, I wanted to compete in the stock class for autocross events.  Aftermarket front sway bars are allowed (funny for a supposed “stock” class, you can even change struts!).  Later modifications nixed this idea, but the sway bar was already installed.  Installation was a pain– the steering rack had to be unbolted and moved in order to get the stock bar out.  Because of clearance issues, the Nismo bar is barely thicker– but it is quite a bit stronger.  The car DOES seem to handle a bit flatter– but this could really be placebo.
• XS Power 4-1 Header — The QR25DE comes with a catalytic converter placed as a collector for the exhaust manifold primaries.  Unfortunately, unburnt fuel has a habit of breaking apart catalyst, and because of valve overlap, that broken up catalyst can be sucked into the cylinder.  This has obvious consequences– like a ruined engine.  There is a recall, but it does not solve the problem.  The only sure-fire solution is to remove the entire thing, usually by installing a header.  I hopped on a group buy on Myspecv.com, had to wait over a month, but finally received it.  Installation was more or less painless.  Fitment was a bit iffy– there was no keyway for the header, and it had maybe 1/2″ of vertical play.  Hopefully it’s lining up.On stock cars, the 2nd o2 sensor assures operation of the cat, so a spacer was put in place to fool the ECU into thinking the cat was still there. Another big plus of installing a header is the power gain. Most people see between 12-16hp! I can’t say I felt that, but performance has definitely increased.
• Apexi WS2 Catback Exhaust — The downside of installing an aftermarket exhaust header is that the stock exhaust sounds absolutely horrid.  The usual solution is an aftermarket catback exhaust system.  There’s no shortage in variety, but almost all the systems available are loud, ricey, and overpriced.  The Apexi WorldSport2 system is really the only one, in my opinion, that sounds halfway decent.  It’s also one of the cheapest.  Fitment wasn’t great, but we got it on there.  I doubt there was any power gain– maybe even a power loss!  The piping is much bigger, so exhaust velocity was probably cut down.A video clip of the entire setup:

And that’s that!