Hey,
I have a '97 F-150 4.2 and was wanting to re-do the exhaust, it still has the stock 2.5" exhaust, that exits in front of the passenger-side rear tire and I dont like it at all. I am wanting to get a 2.5" Magnaflow High-Flow Catalytic converter, however, the rear O2 sensor has me concerned over compatibility issues. Anyone know how to fix this or if it will work? Also, I want to get a Ravin Z33 dual-exhaust muffler and then run the pipes straight out the back. Anyone know if this will work? All the piping would be the stock 2.5" and I was hoping I could buy the cat, muffler and tips, and pay Midas the labor and cost of the piping itself. Anyone approve of this? Or see any major flaws? Thanks.
-M

Update: I called Midas today, to get an estimate for puttin those on, and the guy told me high-flow cats are illegal and that he cant do that?! Anyone care to tell me why? And if anyone has any advice how to install a high-flow cat, I might just go ahead and do it myself. Thanks

 

Midas likes to say that to cover themselves if the vechile were to fail emissions. Most local exhaust shops will put them on without a problem. Also most local shops will do a better job in alot of cases, they are cheaper in most cases also.

Your check engine light shouldn't turn on when you change to a high flow cat. If it does, just get a MIL elimator of some type and put it in. I haven't done anything to the exhaust on my F-150 yet, but I had to use a set of MIL elimators when I put an O/R pipe onto my 00 stang. The check engine light went out and never came on again.

 

I believe that it is a federal offense punishable by a substantial fine to remove a working cat.

 

Like Worthirt said, Midas is just playing CYA (cover your a$$). If you were tell go through emission testing and fail one, then tell them that midas said it was OK, they would be the ones to blame. Personally I have high flow cats on my 2000 5.4 and I love 'em. Deeper exhaust sound, more power, and they are more efficient. Also Midas will charge you way to much for the labor, you should go to your local muffler shop and have it done. They can bend the pipe to fit around your spare and run it out the back.
The hi-flow cats I purchased are 50 state smog legal, so I dont know where they got it was illegal, I've heard them say that to be legal they have to be in the same spot as stock. They burn up the exhaust just like any other cats.
Now about your 02 sensor, they shouldnt trip as long as you put them back in the correct spots, and have one before and after your cats on each side. So go for it, you'll be pleased with the results. Good luck with your project.

 

Like Worthirt said, Midas is just playing CYA (cover your a$$). If you were tol go through emission testing and fail one, then tell them that midas said it was OK, they would be the ones to blame. Personally I have high flow cats on my 2000 5.4 and I love 'em. Deeper exhaust sound, more power, and they are more efficient. Also Midas will charge you way to much for the labor, you should go to your local muffler shop and have it done. They can bend the pipe to fit around your spare and run it out the back.
The hi-flow cats I purchased are 50 state smog legal, so I dont know where they got it was illegal, I've heard them say that to be legal they have to be in the same spot as stock. They burn up the exhaust just like any other cats.
Now about your 02 sensor, they shouldnt trip as long as you put them back in the correct spots, and have one before and after your cats on each side. So go for it, you'll be pleased with the results. Good luck with your project.

 

In response to being illegal to replace a working cat, I read the EPA law and it's illegal on any vehicle under 5 years old with less than 50k miles. Lucky for me, my truck is 7 years old with 78k, and you can only replace the cats in the same setup, so I dunno if I can remove my pre-cats then? And a buddy of mine is going to the local exhaust shop here in town, paid $210 for parts and labor to get new exhaust on his 74 Chevelle, so Im gonna call them and see what they'd charge for labor and I'll just get 2 new high-flow cats off ebay and order the Ravin Z33 muffler myself. The exhaust shop should be able to reinstall my O2 sensors, correct?
-M

 

Yes they can.

 

Hey,
I looked on eBay and found the Magnaflow 94000 series that for a few $$ more has the o2 bung already in it at the very rear of the cat, would this be a better way to go since I'm going to be buying the parts myself then taking them to an exhaust shop? Not that I dont trust someone to be able to do it, just thought it might be a little more reliable and easier?

 

The Magnaflow 94000 series single sensor should work. Your pipe should be a 2.25 inch. (don't qoute me on the pipe size, it's an educated guess)

 

Hmm, I measured the diameter of the exhaust pipe that is on there now, and it was 2.5" across, my truck is a '97 F150 4.2 v6 if that helps you any. But as far as my setup: 2 hi-flow cats, Ravin Z33 muffler and dual rear-exhaust, that should sound pretty sweet, right? And hi-flow cats give me more HP I was told?

 

yep, 4.2 is a very good sounding v6. You should be very pleased with the results. Do not go bigger with the pipe, if anything go down to 2.25

 

Any technical reasoning for that? Or just sound-wise? Also, any idea what a reasonable estimate would be for all of this? Parts comes out to roughly $200 for muffler, 2x hi-flow cats, and 2 chrome tips. I figure $200 in labor to weld it all up, and bend new pipes sounds right?! Maybe less?
-M

 

That price is about right give or take a few dollars.
Now about the pipe size you have a certain amount of backpressure that you need to keep low end torque, to much will rob your power, and too less will take away from low end torque. Changing your cats to hi-flows will cut down on backpressure a lot. On my V8 5.4 I have the free flow cats and 2.5" pipe with 40 series flowmaster, I couldnt tell any loss in low end torque, and I hap a pretty nice jump in HP and acceleration. Bigger pipe will equal a deeper sounding exhaust, so it is really your preference. You could do 2.75 and lose some low end but have a deeper tone, or go 2.25 and keep your torque and it'll still sound good, just make sure you have some good tips on the end(3.5or3.75) just tips deepen up exhaust. Just to keep it simple and cheaper stay with the stock size. Changing all your pipe will be a little bit expensive. Good luck with it, let me know how it goes

 

Hey,
I dont really want to change my stock pipe size, I just assumed it was 2.5" cuz thats the diameter of the exhaust pipe that is on there, but maybe the tip is flared out a bit, I wasnt sure how to tell just by looking. I probably wont be workin on this until Christmas time. Im going to college right now so my money is gone for awhile. Im hoping I can get it all done for $450 or less. I'll be sure to let everyone know what I find out as I go.
-M

 

I had the same thing on my stang. 3 inch tips, but after getting under the car and looking, I saw where they flaired out to 3 inches just after the muffler. I found out that the pipes were 2.25 Inch the rest of the way, that is why I said 2.25 was an educated guess.