I have a 1999 RS and I wanna upgrade with a WRX engine. What year engine would be the best fit or does it matter? I also wanna add an aftermarket exhaust to give it that subaru sound. Can I add the exhaust now and add the turbo engine later? Or does the exhaust depend onwhat type of engine. Andfinally, when I upgrade the engine, do I need to upgrade the trans. too or is the stock RS trans. okay for the added power? thanx heaps!