TA_LS1

ok i have my flowtech headers and y-pipe, but i have a problem. will i be able to run cats with this set up or not. a shop told me i would not. so should i just go with no cats and install it myself, or is that too risky. what are my options for cats?

crash4cyl

Run no cats with o2 sims, or cut the flange off if there is one, run two random tech cats, and attach the y-pipe to those. It's your choice. Most speed shops will install the headers for you, or you can bring the car down to chicago land and I can do it. If you pm me I can let you know $ wise.

Chris

teke184

if you don'thave to worry about emissions...why go through the hassle and $$ of putting cats on it??

do the install yourself. headers on the ls1 are a piece of cake. alone, my first time i did it in my driveway in 10 hours.

check out my detailed install page for flowtechs on my 99z

WiseguyZ28

I'm guessing u bought an offroad ypipe then, u can either get another ypipe w/cats on it which u can just swap on for emmissions but not sure if they'll check for them. As long as u get 02 simms or get the code deleted off the computer then u won't get any Service Engine Soon lights unless u messed up something with the install. At emmissions they do a visual check but it might depend where u go so if they do then ur not passin, but any car with LT's won't pass the visual because if the cats are not in the same position as they are with stock then u fail the visual, but maybe they won't know where the stock position is or they just won't care. If they don't do the visual and see u don't have cats then u should be fine because w/ '98+ cars or something in that area, they don't do the sniffer anymore, they connect something to the PCM or computer or whatever its called, as long as it doesn't set off a code ur passing. I see ur in Wisconsin so i'm not sure if they do the same thing up there. If u know somebody who has a catted y that fits ur flowtechs then see if they'ed let u borrow it for a day when the time for emmissions comes, it'll save u some money. If he wants a rental fee give him $20, works out for the both of u, and u don't gotta have a catted y pipe sitting around the house until emmissions time comes again. The install is pretty easy as long as u find good directions. I installed mine along with spark plugs and wires back in may, i never did any work to a car besides the flowpac i installed a couple weeks earlier, i never even changed my oil but next oil changes i'm doin myself. The install went pretty smooth except for the part where the directions i found had a couple dumb steps that served no purpose and were kinda hard to fix, and the rounded bolts that were on top of the passenger cat which i used a dremel to cut off and that was still kinda hard. If u run into any problems just post it and somebody will answer.

If u don't have them already i would do the sparks plugs and wires right now. And the tools ur gonna need are pretty basic hand tools so i'm sure u have them already.

Crash4cyl, ur not too far from me, i work out in schaumburg. What major intersections u at?

TA_LS1

ok i probly wont run cats then b/c we dont have emissions checks here. but i do need O2 sensors b/c the flowtech y-pipe doesnt have them. where can i get them from? or do i need a different y-pipe?

96SFLZ

You don't need the rear O2's, just the front.

If you don't want to look at the SES light though, you'll need to either: Buy two O2 simms (for the rear O2's) or have the rear O2's deleted from the PCM.

TA_LS1

so what ur saying is that my engine performance wont be affected and my engine wont be harmed if i delete the rear O2s? b/c a mechanic told me that not having the O2s would be bad for my engine. if i do want O2 sims, where should i get them from, and how much would they cost? thanks

96SFLZ

You'll be fine w/o the rear O2's. Your mechanic might have been thinking about the front O2's...you do need those.

O2 sims run about $40 or so a piece. I'm sure www.thunderracing.com has them.

WiseguyZ28

Not sure if u understand how it works but our cars have 4 02 sensors, 2 on driver side and 2 on passenger side, and those two are divided up again, 1 before the cat and 1 after the cat. Since u r running the offroads, u only need 2 02 sensors. In ur headers, u should have a hole bout 1/2 inch diameter if i remember correctly and when u do the swap, u unscrew the front 02's and screw them back into the new headers. As for the rear 02's which would normally go after the cats, u buy the 02 simms which 96SFLZ said were bout $40 each. The 02 simms pretty much just hang there, the 02 sensors are connected to a harness type thing with a little latch snap in kinda thing, u just snap out the rear 02's after u unscrew them and u don't need those anymore but do keep them just in case one of ur front 02's goes bad, u can just swap that one in i'm sure. 02 sensors do cost about $90 i think so make sure u keep those even though u won't need them unless the fronts do go bad. But basically, the 02 simms are just little dead end kinda box things that trick the computer into thinking u r running cats and it tells the computer the cats are working properly when in fact they aren't there.

When u get the 02 simms make sure u also get 1-2 extensions. With a stock header or any shorty header, the header collectors are further up and the front 02's would screw in at that point. With LT headers, the collectors are further down so ur gonna need 1 or 2 extension harnesses to reach down that far. Extensions run about $20 each. I think u only need one but i used two, maybe it depends on the header choice so just check that out with someone else who has flowtechs.

WiseguyZ28

I was up at LS1tech and passed by one of their stickies which i think would be very helpful to u, this JRP guy knows what he's talkin about.
http://www.ls1tech.com/forums/showthread.php?t=139142

TA_LS1

so basically, i dont even need O2 sensors for engine performance? they just prevent they SES light from coming on? also, my headers came with paper gaskets, and ive heard that the metal ones are much better. is this true or am i fine with the paper ones? i was reading the flowtech guide and it said that "breaking in an engine with ceramic coated headers will result in damage to the coating and will void all warranties" does this mean that this could void my 3 yr 30000 mile warranty? i have heard that unless they can prove that the aftermarket mod caused the problem, then the warranty wouldnt be voided. my car has 62xxx miles, so i would think that my engine is already broken in.

teke184

you are correct...o2 sims are for preventing the SES only....no affect on performance.

and why run the risk with the crappy (from what i've been told) paper, just get the oem metal gaskets and be done with it.

TA_LS1

so basically what i should also get is metal gaskets and stage 8 locking bolts? or am i just fine with the bolts that came with them? i am confused with the accessories needed for header install.

also as long as im doing headers should i think about a cutout too?

WiseguyZ28

U need 02 sensors on the front. The rears u don't need 02 sensors or 02 simms, they do not affect performance, only set off the SES light. I'm not sure if u put in 1 too many X's but u said ur car has 62xxx miles, if u have that many miles ur engine was broken in a long time ago and with that many miles u don't have a warranty anymore. GM warranties are 3 years/36000 miles. I'm guessing the warranty they are talkin about is the coating warranty because it does go bad eventually, and the snow we're gettin in a few months won't help that one either. U can prolong the life of the coating by keeping it clean if i'm not mistaken.

U should be fine with paper gaskets but i would go with metal gaskets just to be safe, i used FelPro gaskets on mine, ran me about $18 from an autozone. Just call up a shop around u and ask if they sell them for ur car, not sure what shops u got out there, a pepboys, autozone, napa, otherwise just go with the OEM gaskets from the dealership. And for the lockin header bolts u should also be fine again with the supplied bolts but i also went for the stage 8 lockin header bolts.

If u do the install urself then just get everything on without the cutout. If u have a shop do the install for u then just have them put on the cutout while they're at it. The cutout needs to be welded on so unless u can weld urself, i would say wait and if u feel the need for a cutout then go for it, all its gonna do for u really is sound, very minimal gains if any. Up top u do get more power out of a cutout but how often are u up top goin however fast.

TA_LS1

thanks for all the advice. so i will get the metal gaskets and maybe stage 8 lockin bolts. if all goes well, i should have the headers on this sat hopefully.