newb question intercooler install

[Zeph240sx]

So i almost got my intercooler up for my 180sx, i tried using a 2" holesaw, i cut the first hole on the battery tray and im trying to connect the first hole with a second hole im about to drill.
The problem is, the hole saw is not going through. Been grinding that spot for like 30min. Im using a corded drill. Are Holesaw one time use only? Is there another better way without buying another holesaw?
Up here is like 25 bucks a piece.

[Quantum-Kid]

Use something with a smaller diameter first to ease the cutting process. if you're piping is 2" think you want a hole roughly 2 1/4- 2 1/2" for wiggle room. start out with a 1/2" or 1" drill bit then proceed a few sizes higher (1 1/2" or 2") continue for a while until you are close to the desired diameter then bust out the hole saw bit. The hole saw bit you used at first may have been dulled by cutting the first whole, buy a new one. Good luck!