Well it might have only 168 hp but that's a shit ton compared to the weight of the car. I've passed so many "sports cars" in my little bimmer. And like you said it is easy to mod, the last person I saw switch out the engine produced so much torque that he added weights to the trunk to stop spinning out. Small car = smaller engine not simply because it can have a smaller engine but because it isn't heavy enough for a big engine. Not to say it can't be done well, just that there are more effective mods than switching engines.