killuminatii20

hi all..i have a 96 crew cab silverado with true duels out the back...the new motor has 15,000 miles on a vortec 350 with a new trans and is gutless as hell(mind you this crew cab weighs 8,000 pounds, but should have more power than what it does). i think my cats are shot...., i haveboth my cats and one sensor before the cat on each side and one after that cat on each sideand 18" glass packs out the back, no mufflers....if i take the cats out and just weld a replacement pipe in...and put my sensors back inwhats that gonna do....is taking the cats out gonna make my truck loud? will my truck even run right without the cats in there?will i get bad gas millage, will the check engine light stay on or will everything be totally fine and get more power out of my truck. the guys at work tell me two different storys....one says its gonna be loud as hell and get bad gas millage and not run right...the other says it will run fine? what do i do....i sure ait gettin new cats cuz they are expensive.

MalibuMaxxSS

I did my old 302 ford, it WILL be lound as hell, I got pulled over often and fined once for lound and unecessary noise after midnight, also depends on your emmissions laws it will most likely fail with no cats,

AS for running bad, you will get mixed opinions, your truck needs a certain amount of back pressure and you will have none, same setup I had, duals no cat, and glass pack straight out back.....on a side note should only be one Cat as well unless you are dual right from manifold but that would not be factory ting, if it is dual cats, then X pipe it and replace only 1

...it will be snappier as in more power, and prolly be worse on fuel, and it is not good for valves and lifters....

one thing take the cat out and replace you glass pack with a nice flowmaster turbo muffler, I did this for about 3 months after I got pulled over, was still lound but not obnoxiously loud. and gives a little back pressure..

.for example, I could set car alarms off in our parking lot just starting my old truck, as for highway driving I will admit I could barely stand it and I was only 25ish when I did this

killuminatii20

yeah i had a feeling it would be loud as hell if i took the cats off...so my best bet would be to pick up some 40 series flowmasters and just do away with the glass packs and cats.?

kcb37

MalibuMaxxSS
That truck does come from the factory dual exhaust to the muffler. It has two inlets and one outlet. I am also curious to know what year 302 you had and what year car it was in? If you cut the cats off the sensors will tell the computer (if I am thinking correctly) that you don't have enough fuel going in the cylinders and your gas mileage will suck. It will also make your engine light come on and stay on. If you put on an x pipe and one cat you will only have two sensors and your other two will make the engine light come on. If you put on two x pipes and one cat the two rear sensors still won't read right. I know it cost some money but the best thing you can do for that truck, unless you are going to race it or something like that is to replace the cats.

MalibuMaxxSS

the 302 was in a 92 F150 Reg cab 5 spd, only had headers into 1 cat, then single exhaust, I cut the cat out x pipe, and duals, straigh to the back, if I remember correctly it never had sensors in the cat, they were before it in the manifold.... emmissions were not very strict back as for gas milage it will depend...there is such a thing as 'to free flowing' that will burn valves, and make it hardre on fuel as it is consistantly dumping fuel in to compensate for all the air movement..

Im confused on the 2 x pipe statement how could you do that??? all needs done is from headers come to an x pipe or h pipe, add couple peices on either side for where the cat used to be and go from there, put 2 turbo muffles on the ends and your done, all I did anyhow, total was about 350 bucks labor included and about 2 hours, remember you will fail emmissions without cats.

MalibuMaxxSS

ok I read more clearly....yes it will be duals from the muffler, but not from the headers, manifolds.....it should come from headers to an xpipe or hpipe, and into 1 cat....from there back to a muffer and into duals.... NOW does it have duals from headers ot from mufflers....if only 1 cat, take it out put in x pipe or whatever, just add a length for the cat, and go from there, you can do duals from headers however I would not, from headers come to 1 and go x pipe and duals from there....the muffler has no real bearing here, just aadd on piece on the end for noise, if you take the cats of however, usea turbo as you said it will help build up SOME backpressure...

golfer

One would think if there are sensors after the cats they will set the CEL after removing the cats. These will have erronious readings since there are no cats to filter the emmisions from the exhaust ...this would likely affect performance . You might have to reprogram the ECU's mapping and/or remove the sensors then terminate with O2 simms.

kcb37

golfer
I agree with your statment, if it only had one sensor in front of the cat it should do alright.
MalibuMaxxSS
Those trucks did come with dual exhaust off the manifold. However they weren't true dual, because the muffler has two inlets and one outlet. The muffler is the only thing that connects the two sides together, on a factory system.