After fitting the catback 3" part of the exhaust, was time to finish off the full system, and install a front 3" pipe to have as little restriction as possible in the system. The front pipe is the pipe that connects straight from the turbo, back to the cat converter.

Fitting a front pipe can sometimes add 5rwkw, so its not a massive upgrade, but can often help the turbo spool up quicker, as there is less back pressure preventing it from spinning up as quickly.

As you can see from the old factory pipe, there is a fair bit of difference between the diameter of the old pipe and the new one.

I also decided to heat wrap the front part of the dump pipe, which helps keep the temperatures down on hard runs, and therefore a freer flowing system when things heat up from the turbo side. The heat wrap is really just a special heat resistant weave, that you wrap around, and then hold in place via a couple of clamps. A few people have reported some good results in keeping overall temperatures down, so was worth trying.

The last photo shows it all installed and in place. Installation probably took about 60-90mins and really just involves removing a few bolts and taking everything out.

Now that the exhaust system was sorted, it is time to run a little more boost and chase a little more power out of the car. To do that requires altering how the engine is managed from factory programming.

I'm not going all out on the RB20DET, as the plan is to swap the RB25DET in later, and much of what fits an RB20, won't fit the rb25. One of the main important ones is the engine computer, and its an expensive item - so didn't really want to buy one, and then have to sell it later on for another one.

So to compromise a bit, I decided to install an Apexi S-AFC, which basically is a small electronic box which hooks into the ECU, and modifies the airflow signal, allowing you to tune the car a bit for more power by making it richer (less air to fuel) or leaner (more air to fuel). As a side feature, it also has a few fancy display functions to digitally read the throttle, airflow and RPM in realtime. They are not engine specific as well, so can be transferred to other cars quite easily.

To the right you can see a bit of the install (an install guide is available on Skylines Australia Forums), and the end result.

I've tuned it a little by hand based on previous experience, and this seems to give the car a bit more pull, but it won't really show its colours until its tuned properly by a workshop on a dyno.

Will be a few weeks before that happens, as I want to install a larger turbo and things I've had sitting around for a few months. No point getting it tuned twice to suit the different setups.