Most Efficient Cold Air intake & muffler for a Chevy P/U 2012 2500hd

[turbo1014]

Dear Duramax experts: I have a 2012 2500hd CHEVY P/U with a Duramax engine. I plan to install a cold air intake , exhaust (DPF) back, plus a power PUC. My question is; what would be the most efficient exhaust and cold air intake combo to go with? Thanks :thumb:

 

[jacobdewey]

Any 4 inch system will be more than enough flow, and I really like my banks intake. S&B makes a great intake too.

 

[Dirtymaxx03]

the dpf back exhaust will not be anymore efficient then the stock one.