98 chevy 5.7 cutting the cats ?? good or bad?

ok. i have 40 series flowmaster exhaust, true dual, dumped before axle! it sounds like s h i t. would rather have it stock. my cats are stock and are still on the truck  this truck has 102,000 miles (a 5.7 350) .. im thinking my cats are hurting the sound of what the 40's should sound like. i dont know if cutting them off will hurt my engine or screw up anything i dont want 2. is it better to just buy new cats and replace them?? or should i just hack them off?


i also thought about getting glass packs 18-24" out the back behind tires with 4-5" tips ... what you perfer??? after fixing the cats  

I told ya in the other thread.  
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Trucks...
1989 150(200k) 33 inch hawgs and a blown 302.
1995 Pathfinder(178k)and still going with 31s.
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Kawasaki 750 (26k) Not ran right since carbs rebuilt.
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jus put the glasspacks and go with 4-5 inch tip  

how big of a glasspack?? 12-24"???

so just leave the cats. what if they are plugged up? just cut them .. screw it. replace later if needed!!
leave sensors just put a pipe in place of where the cats were  

whatever you do, if your looking for a good aggressive sound you need to get the exhaust out from under the truck, otherwise all you're gong to hear is hum regardless of the muffler, also i've noticed that with stock cats flowmaster 40 series mufflers don't make much noise, but taking the cats out will wake them up, but i fyou have to pass an emissions test or anything like that you'll be screwed when it comes to that. i for one like the glasspack sound but you still might not get much sound for the glasspack  

so for a 5.7 would you cut the cats and leave the 40's and go out the back behind the tires with tips or cut the cats and do glasspacks?? how big of a glasspack 12 or 24" and how big of a tip would you go? im doing it today  

Ive had a 97 & 99 both 5.7 vortecs, 97  5 speed no cats blown out 12in glasspack with 5x24 tips sounded great but loud as hell also had flow pros at one time but blew apart so replaced with 18in glasspack good sound the truck loved it when the cats were removed mileage went up power did to, truck ran fine. 99 with auto flow pros with tips when i removed the cats on this truck it hated it lost milage and low end ump but sounded great. budies 98 no cats no mufflers 5x24tips loud as hell ran better after cats removed it almost depends on the truck to how it act to you removing the cats you can also hola out the cats so they appear to still be there and theres a sensor you can buy to make your computer think your cats are still there. hope this helps  

Oh forgot leave the 40s bring the pipe out to the back and gut the cats should sound good, make sure they at least  use 2 7/8in pipe biger the pipe helps make a deep sound the bigger the muffler also makes a better sound. I use to love loud and didnt care about the sound now I rater have good sound than just loud if you can fine both thats perfect ask the muffler shop what they would do to there truck and they should be close to rite.  

im gonna hack off the cats weld a pipe in place leave sensors where they are (not even touch the sensors) and go ahead and go straight back with 2 1/2 to 3" pipe and out behind the tires with 3 to 5" tips. leaving the 40's here what it sounds like ... might go ahead and get the packs just to make more noise. 12inch

thanks for the help  

i went with 12" glasspacks 4" tips cut the cats and true dualed it. havent heard it yet. picking it up 2marrow. im sure it will be louddddddddddddd.

what you think..
flowmaster just sounded like a tin can rattling  

What for the mileage to drop a few miles per gallon. What did you do with the 02 sensors? The computer needs to get some feed-back from the back pressure the cats produce in order to properly adjust the amount of fuel. It might sound nice but let's all wait to hear about it when you get it and drive it for a few days and check it over again. Hope it works for ya.  

without the cats the 02 sensors are going to get crazy readings, drops in power, worse engine runnin conditions, bad fuel mileage, you should get high flow cats, they will keep the 02's in sync with the rest of the truck, run your glass packs or super 40 or whatever muffler you want, curve them pipes behind the rear tires you'll hear a good sound  

i left the 02 sensors there. we didnt touch them . just cut out the cats and replaced with pipe. 02s are still where they were. i've heard of people getting better mileage and more power. but i've heard the bad as well.i can tell you it did free up alot being this truck was from cali and the cats were holding back alot of sound with the 40's...  will see how it goes .... and if it does go bad i'll get high flows. but hoping for the best....  

If you need cats dont get the cheap ones.Look them up because the cheap "high flow" ones flow worst then stock.  
Dying ain't much of a livin'
From my favorite movie.
Trucks...
1989 150(200k) 33 inch hawgs and a blown 302.
1995 Pathfinder(178k)and still going with 31s.
Bikes.
2004 Yamaha TTR 225,barly used.
Kawasaki 750 (26k) Not ran right since carbs rebuilt.
!972 Yamaha mini enduro.The niceest one I've ever seen thats never been painted.
New 2002 f150,fx4,5.4v8,after market tranny coolers and unirol tires.

Hows it workin for you now? Mileage still ok? Sound good?  
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