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Gutted Pre=cats

JOV

Well-known member
Joined
Jul 17, 2001
Messages
111
Location
Vacaville, ca, usa
Corvette
2019 ZR1 Blade Silver Metalic
Has anyone that has the pre-cats or pup-cat on their C5 gutted them and notice any hp gain or performance or emmission related problems ?? Looking into those cats makes me wonder how the exhaust gasses can even go thru them , It looks very restrictive. My Y2K
C5 has 4 total, 2 just below the exhaust manifold and the 2 main cats down stream just before the H pipe :bang :beer Here in Calif they inspect to make sure that the cats are in place but they would never know if the pup-cats were gutted:w
 
H

hawaii-5-lo

Guest
aloha, whats up,Da Hawiian Punch has no cats and no mufflers, straight thru:_rock it is a pretty loud car.:_rock it would not pass emissions to save its life. i know these two situations are totaly different, but i fiqured i say hi. i was thinking of doing the same thing when i put on the 'stingers', and x-pipe.:m later, Todd
 

TODD L GRIFFITH

Well-known member
Joined
Jul 12, 2001
Messages
1,120
Location
Middleboro, MA
Corvette
99' MR Coupe, 04' Silverado 03' ZO6 Sold
Gutting Cats

Did you get a check engine light yet? I heard maybe 5hp from this. I don't really know, but you may want to think about buying those O2 simulators.
 
H

hawaii-5-lo

Guest
aloha, my friend has a L98, all intake pieces are ported, and the car has over 100,000 miles on the stock cats, so in his case, he needs all the top end he can get. i think im going to leave my cats alone and just put the x pipe and stingers. the ls1 cats are suppost to flow pretty good from what i have read here before. later Todd.;)
 
C

c5blue

Guest
loud

i have slp loud mouth exhaust ...without cats ...

it's great loudddddddd sound ... without any problem ...
 
H

hawaii-5-lo

Guest
hum,interesting. did you get any gains or loses,i have never seen a car ,take off the cats and lose power.but i read that i happens:confused,i even took/gutted the cats on my 89'L98,it really ran good after that, and my track times improved by.1 tenth. my other friend just put no cats and straight thru exhaust,on his 91 camaro,really freed up the power.later,Todd.
 
H

hawaii-5-lo

Guest
hey JOV, so what happend? did you do it? how did it feel and sound?later,Todd.
 

JOV

Well-known member
Joined
Jul 17, 2001
Messages
111
Location
Vacaville, ca, usa
Corvette
2019 ZR1 Blade Silver Metalic
Results of Removing just the main cat's and the vette seemed sluggish, exhaust note alot louder thru my Corsa system and exhaust really stunk, really bad. it seemed like I lost torque on the low end and on the top end. Mid range seemed stronger, developed a slight ping but figured running leaner because of maybe the loss of back pressure. No check engine, light so reinstalled the cat's, and my C5 defenitly runs better and stronger with them hooked up . I would not recommend removing them , leave them in place !!:bang :beer
 
L

LEEJANDZ

Guest
JOV

Your exhuast system was designed to run with cats, & your computer automatically calibrates the air/fuel ratio.

How long did you run with the cats removed, and did you leave your exhuast open from the cats back?

You need to have the computer "reset" to achieve better results with your exhuast mod.

Try and get c4c5's opinion on this matter.

:D

JASON *** BRAND NEW MAGNECOR WIRES FOR SALE!!! *** 1979 L-82
 
H

hawaii-5-lo

Guest
thanks for the input, im really suprised to hear that, when i removed the cats on my L98, i gained power thru the whole power band,time slips proved it too. did the computer have time to adjust,

headers, cats or no cats, x-pipe,cat-back=lots more flow/power.

cat-back,no cats,h/or x-pipe,stock manifolds=more flow/less power:confused i was thinking of doing this with stingers and an x-pipe.maybe not.thanks JOV,later Todd.
 
H

hawaii-5-lo

Guest
JOV,after looking several times at my exhaust,i can not count 4 cats, i have 2 side by side about a foot behind front tires.:confused they will be getting a 'hollow' job in just a few hours.i really think the computer would have adjusted if givin a hundred miles or so.when i put my halltech t-1 cold-air intake on ,i drove down the street, car was way down on power.the directions,which did not come with intake,said to disconnect the battery for 2 hours or over night,which i did,the long term fuel trims will relearn in a hundred miles or something like that.and i will tell you that when that time period went by,the car has a noticable power gain,and the track proved that,same with any mod like that.the smell will go away in a couple days,i have done this on many cars,Da Hawaiian Punch did this recently,car was sluggish for a couple days, then it came around,it was more than 5 hp no-doubt,you can really feel it.you will not feel 5hp gain.maybe they added more cats as the years went by?well gotta get ready to leave work and spend an hour to jack up car and begin.later,Todd.
 

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