I have an 03 f150 with the 5.4l. I recently deleted the cats and true dualed it with an H-Pipe and two mufflers with turn downs. When im accelerating between 1800rpm and 2100rpm it sounds raspy. It has stock manifolds and I just want it to have that deep growl without the raspiness. Ove heard multiple ways to solve this issue like adding long tube headers, swapping from two mufflers to a DIDO muffler and also adding resonators after the H Pipe. If anyone can elaborate on this issue I would greatly appreciate it. Thanks in advance.

 

What kind of mufflers do you have on it now?

I'm running a two Flowmaster 40 Delta flows, still got cats, on my 4.7l V8 Dakota and there is no raspiness, it's downright bassy. But not bothersome either.

To the point when I lug it in 5th at ~1000 rpms folks say their windows rattle in their house as I drive by.

Something about the resonant frequency.. basically my truck is loud, but at a very low audible frequency. Scientifically speaking.

 

You are losing power with a H-pipe, you need a X-pipe or a DI/DO muffler with one built in.

The best muffler to give you the sound you want is a Flowmaster Super 40 with 3 inch tailpipes.

 

I currently have two flowmaster 40 series mufflers on it. I had an x-pipe installed and it was even more raspy between the same rpm range.

 

From what I've heard an H-Pipe gives more low end torque which is better for a truck. Same with headers; shorty headers are better for low rpm ranges.

 

I'm not an exhaust expert but why would a dido be better than two mufflers with the H pipe. Would that eliminate the raspy tone at that rpm range. Also where should I install it and will it affect exhaust scavenging.

 

Keep the H-pipe and get a pair of Super 40's.

 

I believe thats what I currently have

 

Put cats back on, run full tailpipes out the back.

 

I'm trying to solve this issue without the cats, theres a rason I took them off. Ive deleted cats on many other vehicles and havent had this issue thats why I'm posing on here. I'm down to the options of trying a dido, resonators, or headers. I'm sure someone has encountered the same issue I'm having and has solved it. Thanks for you input though.

 

An X pipe will help aid in retaining low end torque over an H pipe. However it will also make a more aggressive rasp under wide open throttle.

A direct flow muffler vs a chambered muffler will give you a deeper tone, and less crackle on de-cel as well. Borla mufflers are a great option. I ran dual Magnaflow mufflers on my 2004 5.4L and it was quiet and deep. I eventually got bored of them and changed them for Dynomax Bullets.

On a 2007 5.4L I had I did a single 3" system with a Magnaflow 4"x14" round body and it was a happy middle between my 2004s two setups.