Installed a Tomei equal-length header and overpipe on the BRZ this past weekend. What a difference improved exhaust flow can make. With the HKS supercharger, the car was already quick. But now, it's an animal. I'm very pleased.
An absolutely stellar addition to my BRZ this past Summer was the HKS V3 supercharger. Installed the kit myself with the assistance of a couple of friends on day one. I finished it up in my spare time over the week that followed. 5000 miles in and it runs perfectly and gives the BRZ a pleasant kick in the pants.