Removing rear cats?
02-03-2018, 01:20 PM
#1
Removing rear cats?
Before I get all the hate and all the “why take your cats off it makes it sound terrible” please keep that too yourself because this decision isn’t final it’s just a question. Will removing the two rear cats cause a check engine light to come on? Truck is an 03 5.4 v8 just want to know if so then how could I turn it off?
02-04-2018, 12:52 AM
#4
More then likely check engine light will come on but if you do take them off my recommendation to you is either replace them with high flows or replace your current muffler with magnaflow that muffler will retain more back pressure then most flowmasters or anything like that will. So how to turn the check engine light off is to use the good ole sparkplug fowler trick. Pretty much you get yourself some spark plug Fowler’s from local auto store drill them out screw them onto your 02 sensors then screw your o2 sensor on. After that unplug your battery for about 5 minutes plug it back up and you’re good to go. Also I recommend a tuner “sct” so you can turn all your o2s off and place the perfect air to fuel ratio back onto your truck after removing all cats.
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02-05-2018, 04:43 AM
#10
Senior Member
Like that ever works. 
[/QUOTE]No it won't,- unless your connections leak like hell. Your still within parameter margins running just the upstream more restrictive converters.
You can not run cat less in these trucks, have to run one with the factory tune. Otherwise your AF's will be far out, won't mix properly, your engine will be well down on power/torque.... a loud and obnoxious slug bucket that can't get out of its own way.
You can run 0 cats with a custom tune . You can run just about anything or nothing with a custom tune...stacks even.
Anyway, your good to go, just keep those joints good and tight. That will keep you within parameters...no CEL. If they leak.....fail.
Last edited by Jbrew; 02-05-2018 at 04:47 AM.
