I may be getting a newer F-150 with the 5.4L and of course I want a better exhaust system. I talked to several people and they told me not to run Straight pipes with true duals, because of the lack of backpressure. So what does everyone else think. I perfer straightpipes, because I have them on my 93 and love them. Thanks for the replys!

 

I would imagine that the cluster of cat converters would create enough back pressure. You can always add mufflers to the system if things don't work out.

 

My experience with the exhaust on my 98 5.4 lead me to start at the y and run straight pipes out the back under the rear bumper with 20" long 3.5" diameter chrome slant pipes.Painted the inside of pipes red. Sounds excellent! Before mod truck was silent and got 14 mpg, transmission felt like it was taking to long to shift, and torque was fine. After mod leaving shop noticed a small loss of torque and when the transmission went to shift reconnosence came up thru the cab from rear moderately. This I did not like felt I had made a mistake. Arrived home and everyone loved the sound...So I kept reading post on the message board and finally decided to do the airbox mod. I disconnected the battery for most of the day. Finished air box, hooked up battery and took off on a 20 mile drive. I drove agressive and even did a few wot to 90+. Now the truck gets 17 to 18 mpg every time.The shifts aren't harder just faster. No reconnocense at all. I love it. People ask me after I pass them if I have some special tuned exhaust.. Not sure exactly why but I think I drove too slow when I first got the truck. Computor must have made adjustments and relearned my new driving habit's... It's been 10 month's and still at 18 mpg.No reconnosence thru cab, shifts fast...Torque is down a little from 0 to about 30. But it really jumps if your passing! Lot's of luck... Ford TRUCKN

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Capt. America..,
1998 f-150 XLT.SC.2WD.. 3.55LS rear..auto E40D. 5.4L...Stepside Ground effects..... Billet Pedals..... Billet Grill...... Billet Brake lite.. Oval Mirror.. Bed rails.. Bug Deflector.. Wood Grain Kit..Fog lites.. TPS..Air Box.. K&N..... ss Ford tag..Tint Windows.. overhead/floor consoles.. Mood lights...Blue bulbs. Alarm..Radar..Dashmat... Fire/Ice rear window tint ..conspicuity reflectors... cd changer..mobil 1...... Painted rear Drums....... Helwing Sway Bar......... Dual Exhaust............. Halogen Back-up bulbs.... clear corner lens........
Tail lens covers......... Leather...Floor Mats..... Seat covers..Tow Pkge....
Side window Louvers...... Painted Brake calipers... Custom Captian America Paint Job...dual LED brake lights...Rain guards...... Painted throttle body cover...sliding rear window...

 

the loss of back pressure that many people are concerned about is simply invalid unless you disconnect and remove the catalytic converters. Even then there is substantial back pressure for the engine and air flow characteristics to be present to allow the engine to run. I personally have a 1990 F150 with the 4.9 engine. According to Ford at that time the converters absorber 70% of exhaust noise. I took my truck to a muffler shop, disconnected the battery and had them cut off the entire exhaust system starting behind the converter. It was replaced with a 2 in. diameter pipes straight out the rear. To this day the truck is very quiet with a a nice rumble and because the pipes are double wall there is no echo inside the cab. The torque range is determined by the length of the head pipe. The longer it is, the lower the range is. Unless you change to headers removing your exhaust mufflers will cause no change in this range. What does happen is the fuel mixture to the engine is leaned out slightly and it is important to disconnect the battery for it least 20 minutes allowing the memory in the computer to be completely erased. If you still have hesitation, there are many possible solutions including increasing the grade of gasoline to premium, installing a colder thermostat for the best solution is to put a performance chip in the PC. In terms of true duels there is really no such thing today because smog laws prohibit adding a second set of catalytic converters to allow separate exhaust pipes to be run off of each exhaust manifold. This is a true dual exhaust system. When we run duels off the back of the converter that is not a dual exhaust system but merely from an aesthetic standpoint enhancement as well as a little bit better performance because of reduced back pressure and best of all it just sounds better!

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Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II


[This message has been edited by beechkid (edited 01-27-2000).]

 

Hey Beech, check my sig.

I have a 89 with true duels and no cat, with twin turbos. sounds excellent



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Toydestroyer1@yahoo.com

1993 F-150302/e4od/355 Limited slip. dual exhuast w/o mufflers,2 1/4" pipes with Echo Tips, headers, accel plugs/wires(8.6mm)/rotor/cap, hypertech powermodule, 4 degree advance,Blaster Coil,MSd 6A Ignition, TPS Mod,hopefully roller rockers in the future!!5% dark tint. Alpine cd player and Pioneer speakers.

1989 F-150 XLT 4x4

2000 Superduty CrewCab v-10, auto,2wd, Dad's company truck

 

Hey beechkid,

The 1997 and newer f150s with V8's already have twin cats and resonators, so you can leagally run true duals with these new trucks.


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Chris Thomas
1998 F-150XLT Flareside STX Sport Package, 4.6L Auto 3.55 Oxford White/Gray interior, Factory Anti-theft system
Picture: http://216.147.104.171/Y2K/members/ChrisT/christ1a.jpg
Homepage: Chris & Brandi's Universe
Mods: A.R.E. Decklid/Oxford White with gray fabric liner, K&N filter with Airbox Mod (removed silencer), Tinted Windows, GTS sloted taillight covers (painted Oxford white to match), Removed STX stickers
Audio: Kenwood Truck speakers with 10" woofers, Rockford Fosgate and Alpine Amps, Ford 10 disk CD changer
Future Mods: 3/4 Lowering Kit (Maybe 4/6 if I don't have to change tires at the same time), 20" rims and tires, True duals with Supertrap tunable mufflers, Superchip, Supercharger, Jacobs Ignition, NOS, and whatever else I can think of!!!