1. Subaru is famous for the "Boxer" engine sound. That's because of the header design, with one side being longer than the other. 

2. The GDB cars feature a somewhat crude attempt at an equal length header as seen on this STi. Its pretty twisted and convoluted.

3. Here's the SpeedLab equal length header and up pipe. This particular header is for the twin scroll turbo equipped STi's

4. The stocke header is taken out

5. Here's the stock and aftermarket piece side by side. Note the smoother bends and larger ports.

6. The up pipe also features a less sharp bend than the stocker.

7. This car is equipped with an exhaust gas temp sensor as shown here.

8. We transfer the EGT probe to the new headers.

9. Here's the finished installation