Thread: Straight pipe

I want straight pipes for my 2003 5.4. I'll keep my cats so any thoughts?

Straight pipes are fine, gives you that untamed growl from the engine. Sounds great but keep in mind without the back-pressure from a muffler you will lose a little bit of torque. Not really noticeable, unless you race or tow heavy loads all the time.

Well I've heard the "back pressure " is controlled by the cats. Yes I race my buddy's often too

The cats contribute to back pressure yes, but they don't control or regulate it. Most of the back pressure comes from the muffler.

Damn well I love the sound of straight pipes. I don't want any kind of muffler. Should I get dual straights or y pipe?

Your muffler regulates your back pressure. These modular engines need back pressure. Ur 5.4 will not be the same without back pressure

----------

And will slowly diminish

What do y'all recommend for a good loud setup then?

----------

Not saying I don't believe y'all but I've driven 2 f150s with straights with y pipe and both felt very responsive in throttle response. I'm having a hard time believing that the guts of a muffler are classified as back pressure for an engine.

Well from what I understand these engines use headers versus an exhaust manifold, meaning less back pressure. It's up to the cats and mainly the muffler to provide the needed back-pressure. Too much is bad and so is too little. Taking away the muffler does have an effect on power, like I said though its probably not noticeable unless you race all the time or tow/haul heavy loads. Straight pipes do sound awesome, but it helps to have a muffler. For the loudest system with a muffler go Flowmaster. I have the American Thunder SI/DO exhaust system with the Series 40 muffler and it is pretty loud and I only have the 4.6L V8. If you ask Joe he'll say the Super 10 I'll bet, smallest and loudest muffler in the lineup (especially if you go true dual). But Flowmaster for loudness and it still has the needed back-pressure for the engine.

How bad would it effect racing? I thought straights would help top end. From a dead stop, I destroy my buddies 1500hd 6.0.

Exactly like you just said lol, it helps top end, but it gains that top end power by taking it away from the low end power band. Low end is what gets your truck up and going, acceleration. That's where it will affect you, you'll accelerate a little bit slower, but probably minorly noticeable. And keep up the good work beating those Chevy's!!

----------

You'd probably only notice the effect on the dyno because they aren't noticeable while you're driving. However the low end power loss is there, an of you're in a serious race it could hurt you with the lessened take-off power.