Scholioso

Hey guys. Recently picked up some lg super pro 1.75 headers with catted x pipe & tunnel plate for a stupid good deal. So I'm going to be installing it all here soon, and I've been researching. Just a few questions tho.

Do I need new header bolts? Arp?
How hard is it to remove the stock manifold bolts? Do they snap easy?
Ok to reuse multi layered exhaust gasket? (Gm 12617944 came with headers).
Will the x pipe bolt up to stock over axles?
Headers have a block off plate bolted to the air injection. Leave them blocked off? I live in CA so either way the LT's will need to be pulled in 2 years. Wasnt sure if air injection helps the high flows tho.
Read online to use the rear o2 sensors in the front collectors & to delete the fronts?


I have a 97 if this helps, thanks.

grantv

Factory bolts are fine to use again IMO, and should come out without issue.
I would buy new factory gaskets.
If it's a full mid section it will bolt up to any rear section.
You can leave the block off plates on, but you'll have to have the AIR system tuned out. It helps cold start emissions only.

Scholioso

Idk, I'm weary of reusing stock exhaust hardware. I'm thinking of getting some ARP hardware just to be safe. The kit is like $20. The gaskets look good, but yeah, maybe best to just get new. Those are like $12 a pop. And even tho I just replaced the muffler gaskets, maybe best to get new there too.

dragls

ARP studs is the way to go.

Scholioso

I don't even think they offer studs for the exhaust? I just called them, they recommended 134-1102 or 134-1202 for my headers. They look to be just bolts.

dragls

I have the studs, 434-1301

The set was like $130

Andrew

Manifold bolts and downstream bolts come out without problems, just put PB blaster or the like on them the night before.

neutron82

I have never had an issue with reusing stock bolts and they should be fine unless the previous owner torqued the crap out of them... if you want them to look nice you could use some stainless bolts but they aren't a necessity in my opinion... I would buy brand new gm mls gaskets no questions asked and the lg mipipe will bolt up to the stock axle back, no problems there... whether to use the air pump or not is your call, I prefer not to use it and save some weight since it isn't really needed anyway... you can use the rear o2 sensors in the front location but you will need adapters or what I like to do is repin the rear o2 wires into the front connectors so you can eliminate the adapters, there isn't a lot of room to work in that area so the less clutter the better... you can delete the rear o2 sensors but you don't want to mess with the fronts since they are critical to how the car runs, all the rears do is let you know if the cats are failing and have no effect on performance

Scholioso

Ok, so Tognottis Auto World in sac will price match to online. I'll just buy the head bolts there. If gm head bolts are good enough, then surely arp bolts are gonna get the job done. It's good to know that exhaust studs do exist, but that's way overkill for my needs. I'll buy new gaskets while I'm there as well.

For the o2 sensors. Are you saying to put the stock rear o2 sensors in the front location of the new long tubes? Or are you saying to put front o2 sensors in the front location, and then delete the rears all together? Or you're saying I'll need an adapter to make the stock ones work? Rereading it, sounds like I can uplug the rears, bolt them into the front location, and there's an adapter that lets me plug the rears into the front connectors. Then just delete the rears. That what you mean?

I have 4 o2 sensors that came with a ls3 motor I purchased that was in a c5. I'm not sure what these o2 sensors are from, or go to honestly. I will upload a pic. They seem to have different connectors which is weird. Any ideas?

neutron82

you can use the rear o2 sensor in the front location on the headers and plug the rear bungs on the headers if you don't want to use rear o2 sensors but you will need to have the rear o2 sensor codes tuned out so you don't get an ses light... the front and rear o2 sensor connectors are different so if you are going to plug the rear o2 sensors into the front location you will either need adapters or repin the connectors so they will plug up with no adapters

Scholioso

Ok. So I am going to wait on installing these for a little bit. Gonna order new gaskets online, new Tr55 plugs, as well as an oil filter and oil as it is due for an oil change. So I will do all that at once. So with the LS3 motor I bought, I had a bunch of extra parts. I found 5 o2 sensors. 3 rears, 2 randoms (GM 12611165 not sure what this came on factory, much smaller, very short connections, square connector), and then I found one rear o2 sensor that has the rear to front connection adapter that ya'll were talking about. I think one rear o2 sensor is missing with the other adapter. Oh well. I'll buy another adapter.

Ok, so just a quick question. What is the reason for transferring the rears to the front? Why not just put the fronts in the front and rears in the rear? Just curious. Thanks

ASRoff

my vote....


http://www.jegs.com/i/Stage-8/868/8900/10002/-1

neutron82

most longtube headers front o2 location is further back than the oem manifolds so the original front sensors are too short and won't reach... the rear sensors are a lot longer and will reach so that's why it's common to use them in the front location with headers... as far as I know the actual sensor is the same and only the wire length and connector is different from front to rear

Scholioso

Oh gotcha. Ok, that makes sense. So does anyone know how long of an extension to get for the rears to use all 4 o2 sensors? Since I have a total of 5 "rears" (3 came with the ls3, then the 2 that are on the car now). What adapters have ya'll used? Racetronix has the rear to front adapters for 10 a piece, then 18" extensions for 22.5 a piece. Extensions are rather pricey, but I'd rather pay that than pay $200 for a mail in order tune every 2 years to smog. Plus, I'd have to pay that fee twice. Pay to tune back to stock, then pay to tune it back to "racemode"? Screw that. Anybody else know of cheaper extensions? Racetronix offers 18" & 12" extensions. Not sure what is needed to make the rear rears work. I'm sure someone does. Thanks guys.

vettenuts

My understanding is the rear O2's have a different heater that works better with the downstream placement.

I would also buy either a couple of studs or bolts and cut the head off. That way you can screw these in to hang the gasket and header while you try to get the bolts in place. Once severa bolts are in place you can remove the cut off bolt or stud and replace with your new bolts. Don't use any wrenches until the bolts are in a few turns by hand. Can't count how many have cross threaded the exhaust bolts.

neutron82

I use a small zip tie in one of the center bolts to hold the gasket in place and once I get the 2 end bolts started then I cut off the zip tie and thread in the rest of the bolts, that has always worked great for me

Scholioso

I like both ideas. Neutron's with the zip tie sounds a lot easier though, so I will probably do that. Theres a company about 2 hours from me called Obd Innovations. They are cheaper than racetronix, website is actually updated, and they are cheaper which come on, its electrical wiring, not much can go wrong. I'm going to give them a call today, see if I can't score myself a good deal on those extensions & adapters.

So the long tubes I purchased came wrapped in I'm assuming fiberglass wrap. I assume cuz the past 2 days from touching them, my arms feel like theres little needles everywhere. God I hate fiberglass. Anyways, a buddy said that exhaust wrap is awful and to remove it. He said it can catch fire and can cause rust quicker. These lg long tubes though I believe are stainless steel so they don't rust? Anyways, he said to remove the wrap & have it ceramic coated. However, I think it already has. It has black paint on the x pipe & the headers themselves. But I've never seen ceramic coating so idk

Scholioso

Ok, so I just went out and measured the rear o2 sensor location. The stock x pipe measures roughly 43" from the flange to the o2 sensors. New x pipe is roughly 41" from the flange. Do ya'll think this will be an issue? I was looking at getting extensions, but I'd rather not if I don't have to. Since I have extra rear 02 sensors, I was thinking maybe if I had to, splicing in the middle like 4" of extra wiring? Just to make up for that bit? I know it wouldn't exactly be right, but then again how bad can that be compared to a 12" plug and play extension? Has anyone else needed to use an extension to use rear o2 sensors on headers setup?

neutron82

I think you will be fine with no extensions, my old set of lg's were 1 3/4 and I reused my stock rear o2's in the front location with no issues... I switched to 1 7/8 lg's and the front o2 locations are much closer on those, you can actually use the stock front sensors in the front location on that set

Scholioso

I got that part. Stock rear o2 sensor with rear to front adapters, no extensions. However, I want to use rear o2 sensors as well, so I don't have to pay to have them tuned out. So from muffler flange to o2 sensor location on stock h pipe is 43". On the new x pipe, its 41". So they are located 2" farther back. I have 5 rear o2 sensors. So I'll make 2 of those be the fronts, and then I'll have 2 rears as well with an extra just in case I guess. So all 4 sensors will be "rear sensors". Does that make sense? Just wondering if Ya'll think the stock rear sensors have enough slack to be moved back another 2" or not.