I've got a stock rebuilt engine, Weber 32/36, custom header and exhaust, and that's about it for me. I'm personally in the "it's more fun to drive a slow car fast" camp and wouldn't upgrade my 2002 further even if given a free engine. If I want to go really fast, I've got my 135i. If I want to go even faster, I drive a Tesla. But I have more fun in the slow little 2002 than any other car.