I approached a local muffler shop with the following plan on a new 04 F-150 5.4L.

Using 2.5 inch stainless piping, true dual from behind each cat into a Magnaflow 10791 X-pipe and then through two 14326 Magnaflow mufflers exiting behind each wheel.

My questions are this. Will this cost me low end power/torque? Any of the true dual exhaust guys find they miss their low end power?

What if I went with 2.25 inch piping/x-pipe/mufflers? Would that help retain the bottom end?

The exhaust shop guy insists I will lose low end as well as lower my mileage. He said they have done 04 150 true duals and have had to convert them back. As he also says aluminized is better than stainless so I'm not sure if I can believe him.

Thanks for the help!

 

I ran trues on my 02 5.4 and lost bottom end, there were more than a few times I wished I had it, it did sound awsom though, as far as mileage initially it went up slightly then went right back where it started, aroud 14.5 mpg average.

FM