3.7 Header

[upstate]

Hp can be elusive and expensive. The determining factor for me on how much to spend was usually what I was looking for as an end result. The I5 is a relitively small lump in a some what large and heavy 4X4. If you combine that with 34,35 or even taller rubber without providing substantial additional grunt you might just as well leave her looking nice and pretty sitting in the driveway. The diffs already have all the gear they can hold so more tire requires more guts. The desired end result there-by justifies the means. Is a $900 too much, maybe if you consider what a set of brand name headers cost for a small block bowtie but that's where the end result comes in. What are you looking for, a blacktop queen or an offroader.....

[daniel]

T-Pup, No harm No foul. Just trying to get my point across...

6Pack- I was unaware you had a Manual Tranny. Ive got the slushbox so i wonder what teh difference would be... Well maybe if were lucky they will pop somewhere used or they will be cool and drop the price.

[6pack]

I believe if you check with GM parts that the exhaust system has only one Cat, that being the one built into the exhaust manifold. Two O2s one up and one down stream.The other is a resonator that is removed when installing some of the after market Cat back exhaust systems out there. BB being one of them...

Interesting. My Gibson cat-back started behind what I thought was the rear cat. The header removes the manifold and front cat. This leaves the squashed mid-pipe with something in it that looks like a small cat. Like I said earlier, I didn't see any other O2 sensors along that mid-pipe. What is the purpose of the resonator? Reduce noise?

stubborn3: It's hard to say if it's worth it for you. It's worth it for me. You can see the mods I've done in my sig. There is a noticeable difference in the driving power. Not necessarily in the flat out 0 to 60 for me (maybe because of the 5 speed?), but in the driving on the highway where I no longer have to downshift to 4th gear to make it up hills.

daniel, I think pup has an auto tranny too. Maybe that's why he noticed more of a difference than I did, since it effected his shifting?

[upstate]

My mistake, yes you are right about the secondary Cat. Maybe welding a fitting in pipe and moving down stream O2 behind secondary Cat will solve the SES light w/header header problem. Easy fix if it works....
I really would like to try the header but not if it's going to cause emmisions headaches at inspection time.

[6pack]

Sooo, is that thing on the squashed mid-pipe a cat or a resonator?

[upstate]

Yes, as i said my mistake, the resonator is behind the secondary Cat. Did some research with a GM mechanic friend and looks like the primary Cat is there for cold start emissions only. I believe all states emissions test at operating temp. Maybe moving the down stream sensor to a position after the secondary Cat would solve the SES light problem. Anyone have thoughts on this....

[6pack]

Okay, upstate, that's what I had thought.

It's been almost a month now and no codes. All I had to do was add that little extender thing on the O2 sensor.

Pup, are your certain about those torque numbers? The header bolts came loose pretty quickly. I'm about to tighten them back down again.

Now for the fun news... there's a Colorado truck owner that is making a roots supercharger for the I-5. It's suppossed to be a bolt-on kit for around $4000. He's in the testing phases now. http://www.355nation.net/forum/ottp-over-top-performance/34492-supercharged-3-5-canyon.html It's 30-some pages long at this point but it's mostly kids pissing at each other. The first page has the good stuff, so unless you're a gloutton for punishment, I wouldn't bother reading every page. I'm watching the thread and will let people know what happens.

[trailerpup]

...exhaust manifold torque specs are straight from the manual.

[upstate]

Promising to hear that no SES light has returned.
For those interested found this header on E bay under H3 exhaust parts for $859. Manufactered by KPE. Can't tell if it has one or two O2 fittings.

[6pack]

Upstate, that sounds like the one I got. If it is, it has both O2 ports. I think I had to ask him though.

Pup, I don't know. What do you think if I crank them down more?

[trailerpup]

i went the "just crank them down a little more" route and by the time i traded up to the alpha i had a couple broken bolts. ...found one of them in the skid plate. never did find the other. i'd assume they had to r/r them before they resold it as it was making some noise until warmed up. if the rear-most bolt snaps it could mean removing the head to have enough room to extract it. i look at it this way, if you tighten them down too much, when the header/manifold heats up it expands and rips the bolt apart.

...if you google "loose header bolts" you will find lots of tips. whatever you do, don't use any loctite!

[6pack]

Sounds good pup. The front bolt was really loose, the others were pretty good. When I put the Tomp Plates on the rear, I also noticed a nice sized rust hole in my Gibson, drivers side exhaust pipe. That might be where I'm hearing the noise from. So, time to buy a new cat-back. Any suggestions?

Also, mileage has increased between 5 and 10% so far. I usually fill up around 270 and now I'm filling up close to 300. So that's nice.

[upstate]

Hey 6pack still out there. Any SES lights with the header yet???

[6pack]

Actually, yes. The P0420 code again. But My exhaust is hanging half off at this point, so I'm assuming that could be the cause. My new stainless cat-back should be here Friday so I can install it this weekend. Then I'll clear the code and see what happens. I wasn't going to mention anything unless it came back after my new cat-back was on, but since you asked...

[upstate]

Hey ok, thanks for the info. I installed a BB cat back system about a year ago and am satisfied but without the addition of a good header cat backs can only give a small % of their benifit.
I've been chawing at the bit to install a header but unlike u I don't have one just lying around and they are too expensive for me to just experiment with. Would make a great Xmas gift to myself though if it can be made to work without the SES light....
Keep all us wish we had one's posted...