Midnight SS

I want to gut my cats. I was just wondering if I would have to us o2 shims or if I could use the factory 02 sensor. What performance gains if any could I expect, also how much louder would it be. I have a magnaflow cat-back.
Thanks

deviate42

iTrader: (2)

it will be alot louder.

maybe see 5-7 hp

2000Z28M6

iTrader: (13)

thats bout rite

Midnight SS

Thanks for the quick response, but will I be able to use the stock 02 sensors.

jimmyblue

iTrader: (11)

You will pick up a catalyst efficiency code because
the cats no longer make the rears different from the
fronts. The sensors are fine, the PCM is annoyed.
Pick up a set of O2 sims or get the test programmed
to not report the error.

LS1LT1

iTrader: (16)

Wouldn't gutting stock cats (or even the 'less square' aftermarket ones) cause a bad turbulence/swirl effect in there once they're emptied out.
I guess it's still better than having them as active cats but I think the proper way to do it would be to also put a 'straight pipe' through them.
I'm assuming you're looking to still show as if you have functional cats for visual/spot inspection reasons?

jimmyblue

iTrader: (11)

An empty cat is now a resonator, some say
they sound pretty bad. At the flows I was
able to push with a leaf blower, though, a
gutted cat performed better than a high-
flow cat and worse than an offroad tube
of same fitment.

ddelallata

iTrader: (2)

it'll sound louder , but horrible at the same time as the sound waves/pulses bounce back and forth in there (gutted cats) before finally coming out.