The RB5 came in two guises; the standard and a WR Sport Prodrive-tweaked version. The WR Sport version added some new exhaust parts, some intercooler piping, a re-mapped ECU (Engine Control Unit) and a new high-wing. You could (and still can) buy these items separately and at £2,500 more than the standard car I didn't feel it justified the extra cost - the car was expensive enough.

The Prodrive ECU on it's own was a hard-to-come-by item, so when one appeared on Scoobynet in the For Sale forum, I decided to give it a try and see what the fuss was all about. Here is a picture of the original AE801 ECU as installed in Impreza's manufactured in 1999.

The ECU is located in the passenger foot-well, under a metal kick-plate below the glove-box. Installation is extremely easy;

- first you have to unscrew some clips holding the carpet in-place. - Next, pull back the carpet to reveal the kick-plate. - Use a 10mm socket to remove the screws holding down the kick-plate. - Using the same 10mm socket, unscrew the ECU and disconnect the electrical connectors.

Here are some pictures to illustrate these points.

carpet clips

kick-plate screws

ECU screws

Obviously, once the original ECU has been removed just reverse these steps to install the new one.

The PPP ECU is really an STI ECU that has been re-mapped by STI (not Prodrive) to operate on UK cars. It is a very conservative remap which increases boost from around 14psi to 16.5psi, raises the ECU's fuel cut and modifies areas of the fuel/load maps.

Needless to say, not being overly impressed I soon sold the ECU.