I think you will be fine with a cat back system but you need to be aware that Ford sent a memo to all dealers concerning exhaust modified vehicles. Should you have any problems with the heads, head gaskets, plugs or coils, you may be denied any warranty claim. The problem is that should you alter the amount of gases that flow thru the EGR system, you will be raising combustion temps and head temps. If a dealer deems that you have altered the flow- you're on your own. Just a heads up.

 

I haven't found anything to back up my backyard mechanic theory on that yet, but sounds like Ford is full of it. I would think increased exhaust flow would reduce engine temperature. A better breathing engine should be a cooler engine. The cooling system should also prevent excessive heat too.

 

I built a dual sysytem, removed the rear Cat only and used the Hooker Aerochamber mufflers. I have a pipe out each side behind the rear wheels and it sounds very deep with no resonance.
The reason for removing the rear cats was that it was very quiet with all four on and I thought that going through the effort and expense of a full dual system would be futile with them in place.
Anyone looking for a less obnoxious sound to the louder flowmasters might look at thses Hookers.

 

my f-150 5.4 has glass packs with 2 3/4" dual tips and it sounds good

 

i got a gibson single exhaust. love it not too loud put adds to the driving experience. dont think it gives me any more hp. like the kandn filter.. thats a joke

 

If this is the case, how can Gibson say this on its website:

WILL IT VOID MY FACTORY WARRANTY?

No, all of our street exhaust products are 50-state street legal. Our headers are 50-state legal and c.a.r.b. approved. In fact, it is illegal for a dealer to deny you the oe warranty because you have changed the exhaust system. For more details, contact sema, the trade organization of the automotive aftermarket which has been instrumental in protecting such consumer rights, at www.sema.org and they can refer you to the magnuson-moss warranty act of 1975.

CAN AN AUTOMOTIVE DEALERSHIP VOID YOUR WARRANTY?

Your rights are protected through the Magnuson-Moss Warranty Act, 15 USC, 2302, and the Clean Air Act, 42 USA § 7541.

You have the right to buy high-quality, reliable aftermarket performance and replacement parts – an affordable and convenient alternative to the vehicle maker’s parts.
You have the right to use high-quality aftermarket parts and know that your new car warranty claims will be honored. In fact, your vehicle dealer may not reject a warranty claim simply because an aftermarket product is present. A warranty denial in such circumstances may be proper only if the aftermarket part caused the failure being claimed.
You have the right to patronize independent retail stores for vehicle parts and installation. The U.S. aftermarket offers the world’s finest selection of aftermarket products that satisfy the most discriminating customers seeking personalized vehicles for today’s lifestyle.
If a dealership denies a warranty claim and you think the claim falls under the rules explained above concerning the clean air act (such as an emission part failure), obtain a written explanation of the dealer’s refusal.

I'm not challenging you Flash - I'd just like to know a concrete answer because I've heard it both ways. I don't want to do anything to my truck if the possibility of voiding is out there. So who's right?

-aaron

 

Why does everyone recommend Flowmaster? They are so old school. Magnaflow and Bassani are the exhaust systems used by Mustang owners these days. Since they are the true gearheads, they probably know what's best. I had Magnaflows on my 02 Mustang GT and they sounded a ton better than the backfiring flowmasters from the early 90's. Their cat back kit straight from Magnaflow, which is high, is priced at $566.78. Better deals can be found by spending a couple minutes looking. It's a stainless steel system and they claim a 9hp and 11 ft lbs difference just by bolting on a cat back.
http://www.magnaflow.com/02product/cat-backs/ford.htm

 

I have one of the force II flowmaster kits that is dual out the side and it sounds great. Very deep and mellow when accelerating and only a little louder than stock on the highway. It doesn't backfire or sound obnoxious, but it does turn heads on occasion. It actually has less of a drone than the gibson system I used to have when cruising, but sounds much better when you get after it. The kit came with a 50 series truck/suv muffler. You could just have a muffler shop do the piping and purchase the muffler you want if there isn't a kit available.