ok, i am still really confused. how come it is ok to use 3 inch pipes with open headers, and high flow mufflers on pre-smog cars (classic) but it isnt ok to use it on the modern cars? i was never planning to remove my muffles, that would be too loud. i was planning on installing some magnaflo's or hooker high flow mufflers. but thanks for all of the help

 

You can get true duals around here (Dallas) with chrome tips for about $379-$400. Try looking at Spintech for a complete true dual system.

http://www.spintechmufflers.com

 

thanks bro

 

69 - You don't want to run an low backpressure exhaust on your F-150 because the engine is cammed and the drivetrain is geared to produce low end torque and the motor has a low redline (~5000 RPM IIRC). A low backpressure exhaust reduces scavenging at low RPM's and this reduces low end power, if your motor was cammed and geared to rev higher then big headers and big pipes would be a good idea for making power at those higher RPM's where more gas is being pushed down the pipes.

The classic cars that you are referring too likely have more aggressive cams, higher redlines, and more displacement, all of which require better exhaust flow. At higher RPMs and with more displacement you are pushing enough gas down the exhaust pipes that scavenging starts working again. I've never seen a 5000 RPM redline small block (289/302) run worth anything with a big exhaust. I'm not saying you can't run a small motor with a low redline on a big exhaust, it just won't run as well or make as much power as it would with more backpressure.

 

That is the key to performance. Increase the flow rate per cross sectional area, the speed of the exhaust if you will. If you increase the diameter of pipes too much, the flow rate stays the same, yet the are increases and therefore the speed is lower, liekwise power. This applies to every motor, not necessarily highly modified ones. The key is finding the right diameter for given displacement.

The rest of your post is misconception and has little to do with any perfomance gain or loss on a given engine. There are proven benefits for true dual on a stock F-150 motor over the OEM system.

 

thanks guys

 

Here is a good one for you... I completely custom made dual Flowmaster exhaust that exits in front of the pass. rear tire like the lightnings. Now here is the kicker... I put the front O2's where they belong, and used an Ebay simulator, but still get the "Check Engine light". A guy I know said I need to either hook just the heaters of my O2 sensors up and the tie them up under the truck, or find a resistor that has the same resistance as the O2 heater. If anyone has delt with this, PLEASE Help..... I was told that Ford uses a smart sysytem that detects the heaters are not in use along with the sim. wire.

 

A Cost alternative that I'm choosing to do is, purchasing a used dual setup from a lightning. I have already purchased it for 150.00 and I need to extend the length of pipe to fit my Sup. Crew. Thats it plan and simple, the Lightning exhaust already has the set-up that I want, including cats, preheaters, sensor mounts and its already a dual set-up. And it should bolt right up to the existing mainifolds. No buying eliminators or costly aftermarket systems.

 

I thought I would interject here...

It can be argued that what works best will dominate over time.

Magnaflow (or any good straight through muffler) will provide the best flow with a great sound.

Magnaflow also has a flow-engineered x-pipe that helps to make the torque curve very flat. Not to mention, the high-flow cats.

With that said, I'd go with your choice of a good straight through muffler (2 SI/SO or 1 DI/DO), Carsound (magnaflow) cats, and the X-pipe. You've got a true dual setup that sounds AWESOME and gives great power. I had mine done with a new crossover pipe for $200 (not including parts). Just keep looking, and you won't have to worry about CE lights or anything, you'll have true dual exhaust, and you will have more power.

-Flea

 

Most people tie in to their exhaust downstream of the second set of O2 sensors and just leave them in their original locations. It makes it all easier to do and does'nt involve any 02 issues that might throw a code..

Good luck.

 

I'm with Silver Bullit, i have no cats at all, and running MIL eliminators. I had Magnaflow High Flow cats, but i didnt think it was loud at all, i ripped them off, and now the flow and sound is 100 times better than any cat set up. I'm also running true duals with Flowmaster 40's dumped.


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