I,m looking for an exhaust system for my truck.
I still have the original exhaust from the BD downpipe to the back of the truck.
The BD downpipe was 4 inch I believe ,and the original that we weld to the BD downpipe is still 3,5 inch or so.

What is the best for me to buy ? and will it give me some additional horsepower/torque ?

I,m not after a stainless system ,I thought those are more expensive too ?

Thanks

Sterling