helo guys, im trying to help my cousin out with his 98 f150 4.6L. he wants headers but he thinks itll mess the engine up or the computre up? will shorties do any good on his motor or should he get longtubes? if he gets longtubes will he be deleting all the cats? so therefore will he need o2 sensor eliminators? and he plans on running true dual with a H pipe but doesnt know what muffler he should run? he doesnt like the glasspack sound but wants it to be fairly loud. and he plans on dumping it i think, just to be cheaper..so any suggestions? Thanks Andy

 

If its his Daily Driver,my suggestion is to leave well enough alone
Eliminating Cats,and 02 sensors will definately make the engine control system go nuts,not to mention its illegal.

 

he can go to a shop or get a tuner for the cats...and its not illegal in OKLAHOMA! i have a mustang with no cats and we dont have emmisions in oklahoma..but will shorties do anything? or should he get longtubes? what mufflers are the best?

 

Technically it's still illegal in OK. we don't have inspections or emissions anymore, but by law any vehicle has to have ALL systems functioning that it was built with. Thing is without inspections most everyone gets rid of emissions related parts. But, if you got stopped by the wrong officer who knows what he is looking at, you can be given an improper equipment fine, plus a couple others.

As for the original question, magnaflow offers highflow cats that bolt right up to a set of their headers. Then u can keep the O2s, get better exhaust flow, and be less likely to confuse the ECU. I work for a high performance shop, and that's usually the direction we suggest for a DD. I really want to do that setup on my '00 Harley F150. The PO had the original exhaust changed. It has 4 cats (original) that go into a Y pipe. From there they cut the OE tuned HD exhaust and replaced it with a single 3 3/4" pipe flowing thru a 4" flowmaster. Then the 3 3/4" continues all the way out back. It sounds great without being too loud. My plan is to replace the stock cats and manifolds with the magnaflow setup, considering I can buy 4 cats already welded to the proper Y pipe AND the headers for about the same price as 4 OEM cats.

 

A little deeper; this is a heavey truck so you will lose low end torque and may see some high end rpm benifit.
If you run all the time at 4000 rpm then yes they will do something for you but at normal driving No.
The front Ox sensors need a port to sample "all" the cylinders on 'each' bank close to the heads because there is sensor reaction feedback timing involved. Can you do that?
You need a port in the proper place for the rear sensors in the middle of the rear cats or there will be a CEL lamp on with a 420 code. Can you do that?
Running without sensors using fake plugups forces the PCM to run on fixed fuel tables with no full fuel control and results in worse fuel mileage plus sensor codes.
Is there provision for EGR tube from the drivers side? Without this function a code will be set for EGR failure and worse fuel mileage results.
My opinion is not to do this for the little benifit vs cost you think you will get in perforemance and poor mileage.
You can't feel any power increases less than 10 hp and it usually occurrs at higher rpm where more air is passing through the motor.
The computer is in control so you cannot break into the hardware for any worthwhile change unless re-programming is done.
If you feel this info is wrong after asking, do it to it and be happy with the results.
A least I explained the reasons, what the likely outcomes and whys for you to consider.
I won't try to convince you further if you know better.
Good luck.

 

ya i know all the problem with headers. just wanting a straight forward answer if i can do longtubes on his truck. and if shorties will do anything performance wise. and what is the best muffler

 

Yes to LT, probably a little for shorties, mufflers....hhmmm:

Headers:

HEADERS CHROME FORD 1997-2003, 4.6L, 2/4WD, F150/EXPEDITION, WITH FEMALE EGR FITTING at Doug Thorley Headers dougthorleyheaders.com

http://dougthorleyheaders.com/graphi...catalog-LR.pdf

They have shorties too and you can read their propaganda. They also have mufflers. "50 state legal" they say, which means your sensors and EGR will hook up so you avoid the issues as per prior posts.


Now here are some posts about these engines. I think you are pre "PI", which is "Performance Improved", so the later heads are an example of performance improver for the older motors:

https://www.ford-trucks.com/forums/1...-upgrades.html

More basic advice, but if you want to go nuts, read the HRM link:

https://www.ford-trucks.com/forums/1...-can-i-do.html

 

Long tubes all the way. In fact, LTs will IMPROVE low-end power over the untuned, unequal length, shared primary stock exhaust logs... or real shorty headers.

He will need a tune, it's not uncommon for extensive exhaust mods to slightly lean out the A/F ratio. He will also need to turn off the rear O2s in the tune to prevent a CEL if he goes without cats.

Don't expect much gain from bolt-ons with a '98 4.6, which has poor flowing heads, tiny cams, and an extremely long-runner & convoluted intake manifold. If he really wanted to step his game up he could swap on a PI top end, which would bump his compression up 1.5 points AND provide more head flow and slightly larger cams. But expect a custom tune with less timing AND 93 octane if he goes that route. But it would be MUCH more responsive/torquey with that compression, and probably get better fuel mileage as well.

 

well as of right now i think hes just going for nice sounding exhaust..and some better HP and gas mileage at same time too