Dusty?

Hey guys did some searching but wanted to throw up a post and get some help from the pros. I've got a 2006 F150 5.4 just purchased it a few weeks ago. The previous owner had installed a 2.5" exhaust with a SI/DO muffler with dual 3" tips that exits straight out the rear bumper. Short story I hate it hate the sound and hate the look lol. I want to do a new system but aren't familiar with the newer F150's. I had a 2003 F150 4.6L bottom cats removed, high flows in the top cats, 3" into a SI/SO Dynomax ultra flow muffler, side exit with a 5" tip. I loved the sound and look and would like to have something similar on the 2006. 1- I've been told to remove the bottom cats but leave the stock top cats because they are already high flow cats any truth to that?
2- If I do remove the bottom cats do I need to a tuner to turn off the sensors?
3- Should I look at running headers long tube or shorty's
4- Dynomax ultraflow a good muffler on these trucks sound wise and performance?
Any tips, suggestions, help, about anything would be greatly appreciated.

rkneeshaw

These trucks only have one set of cats that I know of. Its not like modern cars that have pre-cats built into the manifolds...

I'm sure if you remove the cats you'll ether need to install CEL eliminators in place of the O2 sensors, or find a way to reprogram the ECU to eliminate the post-cat O2 sensor checks.

Get shorties if you want minimal low end power improvements, zero top end
Get long tubes if you want top end power and are happy to ditch the cats (long tubes replace the cats, shorties do not).

Dusty?

Anybody else want to weigh in on the subject?

nfldfordman

I can strongly recommend a SI-SO magnaflow muffler. I can think of a couple other respected quality brands as well. I personally am not a fan of dynomax, but if you liked your old one you'd probably like it on this truck - little if any difference in sound, running well.

I'd leave the cats alone, I too was under the impression 11th gens only have 2.

if your engine isn't modified, leave the stock manifolds on.