I called my dealer up and asked what performance parts he had for an 05 cobalt and among the usual parts he listed an "extruded honed exhaust manifold". Has anyone else come across this? Also, what kind of benefit should I expect if I was to have it installed? Would it be anything significant enough to warrant the upgrade? For those of you who are curious he quoted the part + installation at $465

 

or you can pay for the part and install it yourself. just my .02 cent.

 

save your money and get the Scdyne header or the one from clear image

 

I understand the GMPP manifold will not give you as much of a gain as a true header would. The installation should not be too hard, however there is some cutting of the stock exhaust involved. If you are comfortable doing that work yourself go for it. If not have it installed by the dealership. If you want to maintain your warranty go with this manifold and pick up the GMPP exhaust.

 

No there isnt...

I installed my own and I didnt have to cut crap

 

I could be wrong, I do not have this part, I'm only going off of what I have read on this board and heard second hand.

 

i keep seeing this part mentioned and it seems to have a pretty divided view on it. what i'm wondering is what would happen if i internally coated one.

http://www.swaintech.com/store.asp?pid=10971

would seem to me that it could make a big diff since the number one issue with cast manifolds under hard use is cracking

 

look, this is a stock piece that has been extruded and honed. It flows 30cfm more than the stock manifold. A header will gain more but this isn't a 'header'. I got 4hp and 6ft/lbs of torque from it. There is a definite performance gain from it and it shows in the upper rpm range and in the 'seat' dyno. You'll also notice a different sound from the exhaust. How mch will you gain with the 2.2 ? I'm not real sure, it should be something though. $465 sounds about right, maybe a bit high. The part, I can get for $280 and labor is 1.3 hours. This is a real simple mod you can do yourself in a few hours with a lift or jackstands. There is nothing to cut or move or even fabricate, it bolts up just like a stock manifold would (thats because it looks stock from the outside.) The only thing you may want would be a gasket. No, it doesn't come with one and you have to buy one if you want it, or you could reuse the old one.

 

I think it would be a waste of money, unless you had it, or the stock one, and you removed more material prior to using that coating.

 

i'm more worried about underhood temps and long term than a few ft/lbs of torque.

 

Thats interesting, never thought about it. Although I haven't seen my engine run any hotter as a result of the manifold being replaced. I haven't had it coated though, so I wouldn't be able to tell you if it would work. I would think that it would have to have more material removed otherwise it would close up and not have as much flow. Make sense..??

 

the coating is something like 3 thou of an inch, i don't see that making more of an issue. as far as having anything removed, i'm wondering if i can buy a stock used manifold of off someone, have it honed out and coated for less than the GMPP one. i've yet to see a 2.2/2.4 header that seems to me like it's as far along as the 2.0 s/c models. also,, and this may just be me, but looking at the design, i don't think that the OEM part looks THAT terrible, it may not be as large as the full headers, but it's not all that tiny either. my goal here is to find a way to maybe improve gas mileage while keeping that hood temp down. and if i got a few ponies and some meaner sounding pipe action, all the better.

 

Check around locally to see what it would cost to have it honed/extruded. Let me know, I may be able to ship mine down. Check out what they say about it. I know there is a site, www.extrudehone.com check them out too. I'd do this if it gains more and costs less.