Noob intro and DB-01 Questions

[Mikel]

First of all I would like to introduce myself... My name is Mikel (duh) sounds like Michael if you were wondering. I am an avid scale modeler and recently found myself a job in a hobby store. After much gnashing of teeth and cajoling from my other co-workers I was thrusted into the world of r/c. I was offered a tamiya DB-01 kit unbuilt and untouched for 40 USD. I put it all together exactly as per instructions and enjoy driving it. However I know that with some modification it could go incredibly faster and handle better. I am also aware that this is kit was designed after the trf501x I believe and have seen various ideas of ways to get this car faster and more durable. My questions are what are the modifications I should consider IMMEDIATELY and in the future and also what is the best choice of a motor for this kit. I have looked at dropping a Traxxas vilenion kit in it and other brushless systems and also have looked at speed gems brushed set-ups. Currently I am running the stock 540j and a dynamite speed controller that came with my transmitter, receiver and servo combo. I am not looking for blisteringly fast and am not even considering a round of competitive racing however I would like to see it get stupid. I am not opposed to tearing it apart again should the need arise and lucky me I get a discount on parts that being said money is not a huge issue either... so what would y'all do in my shoes?