I have a six speed in mine out of a WR1 witch Stewart and Dan did the change over for me as it is a very heavy box.Keep the Five speed clutch as it was up rated front shafts but ended up changing them later,Sti prop with the WRX diff and a DCCD controller which all worked but I keep lighting the rear up as it was not a LSD. So my next mod was to put in the LCD diff and STi rear shafts hubs and disc's,bambo,Hardrace rear Adjustable arms plus all the bushes.I have changed the front shafts as I was not happy the way the WRX went in to a STi box but I think I still have the WRX hubs.