The ideal 4×4 exhaust system for off-road riding is made of aluminium. Why? Because it’s inexpensive, yet very durable and performs amazingly well in dry and dusty conditions. I’m not saying stainless steel is bad by any means, it’s just that it’s more expensive, yet it doesn’t give any extra advantages in dry climates.
https://www.factorydirect4x4exhausts.com.au/