Just bought a 97 fld 120with a 12.7 Detroit . Exhaust manifold is cracked so needs replacing. I see bully dogs ceramic coated are 1400.00. How are those for depentability how about Pittsburgh powers? Have any one else on here taken a older 12.7 and done or added things for better fuel milage? Like the case fuel system?. We have not even put it on the road yet so I Don not know what mpg I will be starting at . Hopefully at 6mpg would be nice to start with. Running reefer in midwest.