Marblehead

iTrader: (1)

I have stock manifolds and y-pipe. Any gains from removing the cats? If so, what will I need to do about the O2 sensors?

smokin2001formula

iTrader: (3)

Not sure if it will help since you don't have anything else to help your car breathe better. Changing out your headers and h-pipe will definetely free up some nice power and make your ls1 breathe much better. Maybe try a search on the subject and see if you can get some more info on the subject of stcok exhaust without cats. If you do get rid of them you can pick up a pair of 02 rear simulators pretty cheap from afterthoughts auto. Taking off the cats can draw attention to you so be aware and make sure your in an area where cops won't bother you. Fines for not having them can be quite steep. Hope this helps out some.

GG01SS

iTrader: (1)

I went with the Bassani Off Road Y-pipe, it was a few years ago, but I think I paid about $220 shipped. Bolted right up in 1.5 hours, you will need the two O2 sims for rears. It looks like from your mph your Z has M6 also, you might gain a couple mph. I did mine the same time as underdrive pully so hard to tell what gain. With both mods I went from consistant 12.7s to 12.5s.
If you plan on doing more internal mods in future go with long tubes w/ ory.

Marblehead

iTrader: (1)

I have stock manifolds and y-pipe with an SLP LM catback. I'm putting on gutted cats so I still need the two rear O2 sims, right? I hope because I just ordered them. Thanks!

Ericbigmac83

iTrader: (19)

Either that or get the o2's tuned out. You should be fine. You will gain a little something, nothing noticeable really though except for the change in exhaust smell, lol

LS1C5Vette

iTrader: (11)

Pros - More sound and a FEW ponies

cons - Exhaust smell is strong untill you get the car tuned (even then you will still smell it), Cost of o2 sims/get the o2 tuned out, possibility of a fine

I would get them removed only if you plan on doing headers, I am doing headers and not putting any cats in but I have a diablo sport to tune them out too.

Marblehead

iTrader: (1)

I didn't realize that I would have to tune it. Won't the sims take care of that? Is it gonna run like ****, rich or lean at WOT until it's tuned? Damn tuning is expensive!

Marblehead

iTrader: (1)

Any info to the above? Thanks!

RedWS6 00

You dont HAVE to tune it. If you buy O2 sims it could cost you as much as getting them turned off in the PCM (not sure how much 02 sims are) I turned mine off as had the tuning softwsare anyway.

You car will run fine with cutted cats and O2 sims. Not rich or lean the fuel trims will tune it for you. Also WOT wont be any further off than before you cutted the cats, well not much off, you car may breath a little better, but not much change.

Marblehead

iTrader: (1)

Thanks!! The O2 sims were $34 each. I really appreciate the quick response!!

I thought they were talking about tuning with LS1 Edit. Thanks again.

RedWS6 00

Could have been talking aout any number of tunings packages like LS1Edit, EFILive, HP Tuners etc.., I beleive all can turn off the rear O2's so their would be no need for O2 sims. If you are going to do mods in the future, I would recommend tuning yourself, I didn't have much choice in the matter, I had to tune myself, and the feeling of changing someone and it works feels great.

Marblehead

iTrader: (1)

My friend has a dyno shop and does tuning, which I'll do as needed. I'm just looking for a few extra ponies with the gutted cats. I'll dyno the car with the gutted cats and then I'll know exactly what the gains are, if any are of gutted cats.

RedWS6 00

I would be interested to know and I beleive others would be too, please post your results when you find out.

Marblehead

iTrader: (1)

No problem, I'd be more than happy to do that. Thanks for the help.

camcamaro1991

iTrader: (18)

Rear O2 sensors are only used to check operation of the cats.

Rear O2 sensors are really a emission check. they read the O2 ppm after the cats... check the efficency, so when you put in rear sims they only thing your doing is tricking your ecm into thinking the cats are working properly.

Long tube headers will increase horsepower with a matched y pipe helps the engine breath.

now just stock manifolds with a y-pipe will do very little in hp numbers,
waste of money to buy sims and y-pipe with no long tube headers.

just my 2 cents.

xBROKEx

iTrader: (7)

gutting the cats really wont do anything except make you car a little louder, and make it stink. if you had an ORY you may see minimal gains. But because of the turbulence caused by the cat being not a smooth internal surface and a diff size and shape you wont see any gains

Midnight02

iTrader: (8)

It was worthwhile for me to get an off-road Y when the long tube headers were installed. The primary factor for me was the change it made to the exhaust note and the small performance gain was of secondary performance. At the end of the day, it works out for me perfectly because my car still sounds SOMEWHAT civilized on the highway, however just pop open the cutout and it goes to NASTY pretty quickly.

Marblehead

iTrader: (1)

Thanks for the info. We'll see what the dyno shows...

I just dynoed two weeks ago as well.

Travis99LS1

iTrader: (2)

Hey man i was just wondering where you bought your 02 sims from? I need some, but i cant seem to find them for that cheap. Thanks for any help.

Marblehead

iTrader: (1)

http://www.afterthoughtsauto.com/

Their in Texas. I ordered and received in 2 days!!