CAT questions

[Cruster]

I have a guy who's willing to take off the back cats on my 05 QC. I already took off the stock muffler and left the resonator. The flowmaster doesn't sound all that bad but I'd like it a little louder. 2 muffler shops in town won't touch the CATS (go figure).

Question: will it be much louder? Will it f-ck up the O2 sensor just taking off the back ones?
Any performance improvement at all? All help appreciated:rock:

 

[Hatedonmostly]

I took mine off myself, Just get catless mids, Yes mine got very loud after I removed the cats.

 

[TNVIPER]

Shouldnt have a problem with CELs just removing the rear cats...which I think are actually resonators?....cant blame the shops..something like a $10K fine for messing with cats..

 

[viperhauler]

i believe the rear two are resonators...not cats...

i cut mine off...and it felt like it had a bit more oomph...but hardly noticeable...but i think that's what's caused my magnaflows to blow the guts out, too...so take that fwiw...

 

[SilvrSRT10]

The rear two are not monitored and can be removed without problem. I'm running a stock exhaust and didn't notice any more noise from the exhaust. There have been reports that removing the rear two can give you 40 hp more but I can't verify that. To many it may just sound like you've gained 40 hp.

 

[VENOMOUS1 RACING]

Actually the rears are monitored! They tell the ECM whether the catalysts are up to par or not. You can ziptie them to the tranny reinforcement bars running along the outer sides of tranny. I'm at 10k miles without check engine light. The front 2 monitor a/f ration and report to ECM also. I started with the rears and a slight power increase, followed by the fronts which gave more (maybe 20 between the 4)power. Then did opposite and left the muffler and rid the resoator and she sounded sweet. just wasn't enough so she got a one-off Viper side exhaust.

 

[moparracing]

the rear two cats can be removed without CEL issues & with the resonator that is behind the stock muffler on the '05's/'06's, it shouldn't be too much louder...... as far as HP gains with just the rear two cats removed - little to none.......
now it's a whole different story if you decide to remove all the cats:

http://www.vtcoa.com/forums/showpost.php?p=435119&postcount=2

it's louder but also the best HP bang for your buck too. :rock:

 

[Cruster]

Actually the rears are monitored! They tell the ECM whether the catalysts are up to par or not. You can ziptie them to the tranny reinforcement bars running along the outer sides of tranny. I'm at 10k miles without check engine light. The front 2 monitor a/f ration and report to ECM also. I started with the rears and a slight power increase, followed by the fronts which gave more (maybe 20 between the 4)power. Then did opposite and left the muffler and rid the resoator and she sounded sweet. just wasn't enough so she got a one-off Viper side exhaust.

Thanks everyone for the input. Really appreciate your experience and expertise! The guys at the shop said the first 2 are precats for engine feedback and the back two are unmonitored but I will definitely look again, didn't see any probes or wires on the back 2. Don't want lights all over the dash and have to put them back on.

 

[bigike]

The front 2 are the restrictive jobs..

The rear two are cats. I gutted the front and left the back in. Had the back ones removed once, too much drone in the monster 4".

Search for a article that stinker did a few years ago 17 hp both were good for 20. or so.

 

[eddie102870]

go with catless mids and get simulators for the front. id leave the resonator on the rear to help with the drone unless you dont mind it being a little loud. a x pipe might help with that.

 

[FSTJACK]

go with catless mids and get simulators for the front. id leave the resonator on the rear to help with the drone unless you dont mind it being a little loud. a x pipe might help with that.

The rear cats are the most restrictive and can be removed or gutted without any CEL problems.
An X crossover will help a lot with torque and a little more power.

 

[TREKER]

Cruster.... Your avi is making me feel like...