BassAckwards

A muffler doesn't have a noticeable change in performance. Sounds like they were trying to save you a few bucks?

jprevat

iTrader: (1)

If the design is what you want and the sound is to your liking I would leave it be unless you just have to have the brand name

ClaySlayer

I agree. If it's straight through that's about as good as you're going to get for flow. Muffs are a sound only mod on these trucks (and just about any other modern vehicle). Don't buy into all the hype that these aftermarket complies put out there. Same thing goes for intake kits unless you plan to run above ~4,000rpm all the time.

Coachdwt

I have a 2002 crewcab FX4 5.4. Is there a way to do away with the cats and not have the cel come on? Thank you in advance for any information!

BassAckwards

Programmer

VSB 6.2

So I'm shopping exhausts for my 6.2L and going back an forth. Looking at a tuner later but would like to run a 4" exhaust without a tune. Do you see any issues with power loss running 4"?

chayes627

So glad I found this thread.

I have 2007 5.4 4x4 and the classic exhaust manifold leak on both sides. I will have a 3" SI/SO magnaflow muffler. Would there be any benefit to long tube headers, specifically pacesetter? Adding high flow cats from magnaflow? Y-pipe staying close to stock position and all piping 3", if I would do this. Looking for good overall power, not high RPM only power. Also tuner would not come for about a year.

jprevat

iTrader: (1)

Any piping diameter will shift ypur power band. Im no expert but any gain you see will be minimal without a tuner.

GreatWhite7700

i was wondering if i would see any power gain from running highflow cats into a dual in dual out muffler. If there is any where would they be and how much?

djmcnab

After 15 pages I say THANK YOU Otto! Great info. Here's my conundrum:

I have a leaky mainfold/blown gasket on my completely stock '07 SuperCrew 5.4L Flexfuel. Rather than giving the Ford dealer ~$1000 to return it to stock on one side, I'd rather replace it all with something that works for me.

Here's what I'm going for which isn't really covered on this thread:

I mostly do daily commuting to my office job & occasionally do long haul towing with a 22' enclosed (~7000lbs total trailer weight).

I'd like to add some MPG's for daily driving and a few HP's/MPG's for towing at highway speed.

I don't care about sound & would prefer little increase in dB level.
I don't care about looks or where the exhaust exits.

You state that long tube headers with a straight through muffler are best so I got that. What about single vs. dual pipes before & after the muffler? Which configurations work best for the added HP/MPG I'm looking for giving no regard to looks/sound. If dual then use H/X pipe, I got that much, but over all would single before & after muffler be better/cheaper or not? Now if sound can be made better within the primary desires then that's fine, I'm not opposed so long as it doesn't get much louder than stock.

I'm thinking of perhaps springing for ceramic lined headers to keep engine comp temp down when towing. $$ is not the primary concern for me here, just the added MPG/HP & maintaining good towing characteristics.

Also since I'm having a local shop do the work with custom bent tubing, I'm a little concerned about the effect they will have on the ECM. What questions should I ask about O2 sensor placement in the new system? & what should I look for to be the right answers. Could you discuss this a bit?

Should I look for them to weld new cat's into the system or will the local shop likely eliminate this or try to reuse old (which seems wrong)?

Thanks!