Hi..
Has anyone cut the back two cats off and just welded a peice of tube in. If so how much louder did it make it? Also did you notice any power gain or loses?

 

Cutting off the cats will make it lose some low end, but it will sound very deep and very nice I have 91 F150 and I took the rear cat off and let me tell you I regret that from experience. My gas mileage hit drop dead poor mileage, the truck still ran ok, but not the way it should and overtime the emissons stuff started puking out on me too, because it's all tied together in some fashion. I put the old cat back on, replaced what all failed on me, EGR, and TPS sensor went out. I replaced those and it smoothed back out, gas mileage went back up, and I regained low end. IT is also illegal to take your cats off. As an alternative what you can do, is gut out the insides and weld them back up so you won't get a huge fine when you get busted but you'll still have the sound your looking for.

I wouldn't reccomend taking your cats off but if you wish to do so, go for it. IT will be louder, but if you keep a good muffler on there, magnaflow for instance or flowmaster it should sound very nice. Or what you can do is get some high flow cats, not illegal and will still sound very nice too. Good Luck

91

 

What year and engine do you have? The newer trucks have 4 cats and 4 O2 sensors. There are tricks to play to make sure no codes get set if you (illegally) eliminate the O2 sensors. Performance wise, it depends on your engien and what exhaust you have. Are you thinking of just running dual straight pipes after the frist set of cats? For a stock engine expect to loose some power under 3000rpm. Even the 5.4L all straight would be too much I think, and loud.

 

Thanks for the replys,
Apt, I have the 5.4l with a few bolt on mods. My sig shows the mods. The muffler is a 40 series flowmaster 3in in and 2 2.5in outs. Both come out in front of my right rear tire.

 

Flowmaster despite the name doesn't actually flow too well. Eliminating the cats, going to a new y-pipe (dual 2.5 to 3") and then into your current muffler should work fine. It'll make it even louder and may give you a little power high and low. But I recomemnd high flow cats rather than eliminating them.

What is your goal, loudness? Performance? What about your current setup do you not like?

 

I like my current setup alot, I just wish it had alittle more sound to it. . Its really not loud at all. I think.

 

If you want louder, why not get rid of your mufflers and use straight pipes? At least you wouldn't have to mess with the O2 sensors or MIL eliminators.

 

Well I did that for about 4 months until emissions came around. I thought they would check for a muffler. So I pussed out and went and got one. Well they didn't check for it at all. All they do is check all your safety stuff then hook up a plug to the access point under your dash kinda by your right knee. All it does is read all your sensors and sees if the computer is giving off codes. This type of testing is only done on 96 and newer models. 96-72 have to have the huffer test thing. 72 below just need all the safety stuff. Guess I gotta go out and find a 72 model

 

Hahaha! Mufflers should not be required to pass emmisions tests. If there are local sound level ordinances, that could be a problem, but you shouldn't have any problems with any kind of registration without mufflers, as lon as you keep the cats.