You are always going to have the debate as to why mod a v8 and why mod an econobox. On the other hand, I would prefer to take a slower car with little to none market, and build it how I want to. It's so easy for you to just go to Summit or Jegs, browse through the catalog, and just spend all sorts of money on what already made for you, or you can start from scratch, fabricate your own, actually learn something from the experience, and be relatively fast.
I'm not going to sit back here and tell everyone how my Saturn is the fastest thing, because it isn't. Would I ever own or mod a v8? No. There is no challenge. I would prefer taking a slow car and making it faster (especially a car you wouldn't expect anything from) over taking a fast car and making it faster.