Whats the best thing to make my 2003 blaster go fast

Well tell us a little more. Is the bike bone stock? What are your performance goals? What's your budget? How good are you with a wrench?
 
You want faster, or more power, or both?

Larger sprocket on front, smaller on rear will give more speed, as will larger tyres.

More power, vice versa.

The cheapest mod for more power is a re chambered head, hence you can run larger gearing because of the increased power and gain speed.
 
Without giving a huge list that adds up to thousands ... Head mod, aftermarket intake/air box, port n polish ! That should satisfy your need for speed, for a while anyway haha.
 
What do you have for "mods" now? Bigger/taller tires or higher/taller gearing will make it faster, but will take longer to get there, without more power to do it. BTW, what's wrong with a pipe? That's usually one of the first mods.

Answer the ??? and we'll go from there.