will after market pistons be louder on the evo then the stock piston's?

 

As long as they are balanced properly and have good clearance, no.

 

Talk to a good engine builder. Some pistons have different ratios of materials that can cause wanted, or unwated expansion of the pistons depending on your goals. If it's a sloppy fit at start up and the right combination is used, then the expansion will fill the slop up and you'll get a smooth, quiet running motor. If its wrong you could go so far as to get piston slap, which will make the engine noisy. Buschur or AMS could help you.

 

If you are going to stroke it, well maybe