I am trying to build up a light weight drag purpose only cat back system.

Since open header is not permitted at our strip, I'd like to make something as light as possible.
I can get 2.5" alluminum pipes for dirt cheap, would they hold the heat?
the car would never be running for more than 5 mins at a time since I push it in the line up and then have to wait another 45 mins or so for next turn.

Please let me know what you think or suggest.