I have a 99 f-150 supercab w/ 5.4 4wd. Anyway i just got magnaflow hi flow cats and was wondering how i should hook them up. Should i pull out the 2 pre cats and the regular cats and hook them up or what and what should i do wit the O2 sensors and stuff. help

 

The O2 sensors stay where they are and you have to weld the two new cats in place of the four OEM cats.

I order two 94306 Magnaflow cats that will be here someday. They sent them by ship. So, I will be doing the same plus installing a new 12158 SI/DO muffler plus 2½" x 4"x 18" SS tips

 

You can also just gut the pre-cats and leave the shell intact.

That's what I did, because we have a visual smog inspection here in CA where they make sure everything is there.

 

I won't tell anybody. Honest, I won't. However, there are a few things I need, and I'm not too far from you! I'm thinkin' concert tickets, maybe tickets to a game. I'll think it over and get back to you...or else

 

You'll have to catch me first!

Where are you at in the 909?

 

Have you had any trouble with rattling or buzzing since you gutted the precats?

 

Every once is a while I get a slight rattle, but it never lasts and is very infrequent.

I'm not sure if it's coming from the pre-cat shells or something else, as I also got my duals installed at the same time.

 

Cool. Only reason I ask is that most of my experience with trying to make cars faster is from imports, and a lot of people involved with imports (especially, for some reason, people that drive really low trim like Civics, but that's neither here nor there) loved gutting their cats. That almost always produced the most godawful rattling, buzzing, ****ty sounding exhaust note I've ever heard; and wanted to know if it was similar on our trucks.

If I had to guess, I'd say most of those guys were just doing a half-assed job of it and leaving pieces in there to rattle and bang around.

 

I'm Procharged, but hauling 4 doors and 4WD, so I probably can't catch you. I won't embarass myself, but at just under 6000 lbs. not quite as fast. I'm in Grand Terrace, 'tween Riverside and San Bernardino.

 

thanxs, I think I'm just gonna gut my pre-cats and hook my new cats up. The only question i have is should i just cut right in front of my old cats and weld in the new ones.

 

Well, I'm just a tick OVER 6,000 lbs... and your 2001 has PI heads, so you're making more power than I am...so we'll have to see!

3 tons of fun!

Nice wheels, by the way!

 

If you have a shop do it then they'll know what to do. Make sure you leave enough pipe there to weld the new cats to and you'll be fine.

 

Thanks, yours too! I really wanted an Expy to replace my Explorer back in '01, but they quit making them in RED! And I didn't want to repaint my boat. I'll keep an eye out for you on the road, but my 8-9PSI probably isn't gonna kick your 10.5!

 

hey guys ive got a 2000 5.4 in my f-150 and i think one of my cats is getting cloged, i have a 3" y pipe back exhaust with a 40 series flowmaster. it sounds good untill above 3 grand then i get the classic vacume cleaner exhaust sound. i want to remove all of my cats and replace them with 1 high flow cat right after the y pipe, like the older f-150's had. i was woundering if anyone has done this or has any comments on me doing this, also since im going this far are headers worth the trouble and who makes them for our trucks. thanks!