Hello Fordnatics! I'm new here and I'd like to share my problem with you and see if you can help me.
I have a '99 4.6 and had a custom exhaust installed the other day. The exhaust was cut right at the "Y" and a 3" pipe was welded on. Next is a Flowmaster 40 series,SI/SO. The ehaust was extended through a mandrel bend, exiting out the side in front of the rear passenger wheel. All 3" pipe was used.
I installed a K&N filter in the stock airbox and removed the restrictive plastic tubing entering the fender well. My results and money are dismal at best. I totally lost bottom end and the tranny seems to almost slip out of the hole. Bottom end lag BIGTIME!
I've noticed that most aftermarket exhaust will have SI/DO when exiting in front of rear wheel. Did I do a no,no? Please help!
THANKS!!!

------------------
'99 F-150 Lariat
Flowmaster Exhaust
Polaris Sport 400 ATV highly modified and lightened for 300' sand drags. 0-60 in less than 300 yards, under 5 seconds.
You only live once; so ride hard!

 

I ran true duals on my 97 and installed a DI/DO flowmaster and also a knn FIPK i lost so much power it was unbelievable my trany acted the same way as yours so i pulled the muffler off and welded in some strait pipes it made a world of difference i couldnt believe it i gained all my power and some dont know if that is your problem or not i have 2 1/2 in. pipe i am not really mechanically inclined on these things i just know enuff to get by with home repairs..lol hope someone can help ya
jj
4x4 ORP flare side ex-cab
2 in body lift
33x12.50 bfg at/ko's (geolander m/t's on the way)
centerline coronas
roll bars
kc daylighters (200000cp)
ram-air hood
westin step bars
wiper cowl
true dual straight pipes
4.6l auto
side window louvers

 

Thought I would chime in on this. I just had a Flowmaster 40 SI/DO installed today. The shop put on 2 1/4 pipe back from the muffler. Don't ask me why. I should have specified that I wanted 2 1/2 but...

Anyway, the bottom-end power is gone! I will try and reset the computer but I am concerned about too much backpressure. Does anyone think this is a concern?

Crossing my finges the reset will help! Keep me posted on your results!

------------------
Supercrew 4x4 Lariat
Solid Black
5.4 Triton
3.55 Limited Slip
6750# GVWR Package
Skid Plates
Moon Roof
Sliding Rear Window
Trailer Tow - Class III
Cargo Cage
Grey Leather Captains Chairs
6-Disc CD Changer

Mods:
305/70/16 ATS, AR Atlas 16x8
Chrome Westin Steps

Planned: Dual Exhaust, Toneau Cover and Expedition Console Mod.

Another great Ford truck site -www.fseries.com

Truck Pictures

 

I reset my computer and the truck is still dead from the start. I was told one time that Ford looked good and hard into the design of the stock exhaust. I should have listened to the guy. Flowmaster has no answers either.

 

Not sure now! Reset the computer... it seemed to help. I e-mailed flowmaster. I will ask them what they recommend for the 5.4. I should have asked them first. Oh well, I really wanted to hear the 5.4 Triton come alive!

The bottom end is pretty strong through 1,400 rpm but it doesn't hold long. I don't think it runs as good from 1,500 to 3,000. It does however seem to wake up a little stronger after 3,000 to 5,000 rpm (the engine's first 5,000+ mark )

I spent quite a bit of time under the truck today. When the shop installed the flowmaster they used the OEM right side hangers to fasten the muffler/pipe. It was a little too wobbly for my taste so I rigged it a little with $5.00 worth of hardware. Much tighter now.

The point was I caught a glimpse of the numbers on the muffler - 9425502. It appears the guys at the shop mistook me asking for a Flowmaster 40 and gave me a Delta Flow 50 . Imagine that. Not sure what they were thinking this morning. They also had my tips on before I had an opportunity to check them out. I made them take the them off and realign them. They should have asked!

The Delta Flow is almost too quiet. Hardly any in-cab resonance. It roars when started but my test is second gear deceleration. I love to hear that rumble It doesn't sound as loud as I would prefer. Maybe thats best, the Crew isn't supposed to be a hot rod!

Good luck Red Lariat. Let us know what you find out.

[This message has been edited by kkirt1 (edited 12-09-2000).]

 

Jimmy;
Did you reset the computer? Flowmaster recommended this to me.

 

Going larger in diameter or installing a muffler/system not tuned for your truck can bring you trouble.

My 5.4 is running OEM 2 1/2" piping so, you can imagine what a 3" piping all the way down with a less restrictive muffler can do to the low end of a 4.6.

What I am doing next week is installing a Gibson Super Truck. While the inlet is a 3" it keeps the main pipe at 2 1/2" and exits with dual 2 1/2". If you have mandrel bent piping that's a plus. That's one of the reasons I went with a system like this one.

Based on research here and other places Gibson and Jardine are the best for our trucks.

Welcome to the boards.

------------------
My Ride: 1998 F150 4x4 Lariat Supercab Flareside 5.4L in Oxford White/gold, ORP, Tow Package, 3.55 Gears.

Modifications: K&N FIPK, Stepshield door sill protectors, Performance Accesories 3" body lift, Lift Lips, Gabriel Gas Ryder LT VST Shocks, Daystar front anti-sway bar polyurethane bushings and 35x12.5R16.5LT BFG All Terrain KO's on 16.5x9.75 American Eagle 589's.

Photos at: http://www.communicomgroup.com/jmtruck

 

Resetting the computer helps a lot. Good luck.

------------------
My Ride: 1998 F150 4x4 Lariat Supercab Flareside 5.4L in Oxford White/gold, ORP, Tow Package, 3.55 Gears.

Modifications: K&N FIPK, Stepshield door sill protectors, Performance Accesories 3" body lift, Lift Lips, Gabriel Gas Ryder LT VST Shocks, Daystar front anti-sway bar polyurethane bushings and 35x12.5R16.5LT BFG All Terrain KO's on 16.5x9.75 American Eagle 589's.

Photos at: http://www.communicomgroup.com/jmtruck

 

JM;
Thanks for the insight. Is resetting the computer as easy as just disconnecting the pos. cable on the battery?

------------------
'99 F-150 Lariat
Flowmaster Exhaust
Polaris Sport 400 ATV highly modified and lightened for 300' sand drags. 0-60 in less than 300 yards, under 5 seconds.
You only live once; so ride hard!

 

The sound of the Flowmaster 40 series is real nice in my opinion. I did seem to gain top end. I was looking for trailer pulling torque though.

------------------
'99 F-150 Lariat
Flowmaster Exhaust
Polaris Sport 400 ATV highly modified and lightened for 300' sand drags. 0-60 in less than 300 yards, under 5 seconds.
You only live once; so ride hard!

 

Red Lariat, You said you put a K&N in the stock airbox that could be your problem that flat tube that goes to the throttlebody is restrictive. I put an airaid system on mine and have 3" exaust from the y back. In stock form it would barely chirp the tires now it actually spins them. Soon I hope to add a superchip and really wake it up.

------------------
'97 F150 4.6L XL WHITE,FLEETSIDE R/C L/B, LEER SHELL W/FISHING POLE RACK, BED MAT,LIMMITED SLIP,245/75/16 DESERT DOGS ON POLISHED ALUM, WHEELS.
AIRAID, 3" CAT BACK OUT THE SIDE w/MAGNAFLOW MUFFER

 

Thanks for the info Whiteflight. It's too bad that the exhaust manufacturers aren't a little more honest on the low end loss.
This did teach me one valuable lesson. Ford knows how to make an exhaust!

------------------
'99 F-150 Lariat
Flowmaster Exhaust
Polaris Sport 400 ATV highly modified and lightened for 300' sand drags. 0-60 in less than 300 yards, under 5 seconds.
You only live once; so ride hard!

 

I just called Flowmaster the other day and the tech I talked to said to replace the existing stock muffler with a 70 series muffler in order to keep or improve my torque and hp. He warned me about opening up the new Fords to much since the engine thrives on backpressure.

------------------
1999 F150 S.Cab 4x4
Northland Edition,5.4
Off road pkg. Fleetside
Black w/grey int.

 

Thanks Bob. It's funny how when I called Flowmaster; they acted like my case was unique. What about the catback systems they sell for Fords? This goes against what they're telling you on the phone.

------------------
'99 F-150 Lariat
Flowmaster Exhaust
Polaris Sport 400 ATV highly modified and lightened for 300' sand drags. 0-60 in less than 300 yards, under 5 seconds.
You only live once; so ride hard!

 

Red Lariat,
I've called Flowmaster several times and have had the same response each time about the 70 series and keeping the same dia. pipe, mostly because I have been up in the air on what to put on my truck. This last time I asked them why they don’t make a force 2 system like the Dodge system which is a single in / out 3 inch with a 70 series muffler. The tech said that there was not enough demand for it from the Ford people. I then asked him about opening it up with a 50 series delta flow and he did not suggest opening it up that much in the fear that I would loose my low-end torque. Then I asked him why the system they sell is open even more than that with the double out 2 1/2 inch. He said that is what everyone asks for so that’s what they make. I suppose its just demand driven. But I think I've made up my mind to go with a 70 series and keep my existing pipes. Although it will be quieter than a 50 series it will have a deeper toned rumble that is more felt than heard.


------------------
1999 F150 S.Cab 4x4
Northland Edition,5.4
Off road pkg. Fleetside
Black w/grey int.