I just had a passenger side exhaust manifold crack and where the Y pipe attaches it seems to be rotted out.

From the exhaust shop, they want to install in a new manifold, crossover & converter (which crossover and converter come together/one piece that model) and bolt it to my existing exhaust which isn't that old, for $600.00

I have a buddy that can order my Y-pipe and manifold for 285.00 (10% over cost) and his son who builds race cars install it $200.. total $485 (save me 100 bucks)

Both of the above examples do not include the O2 sensor if I cant re-use the old one.


Or...

1. I can buy a set of stainless steel headers off a company on ebay with a great reputation. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=013&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=230180129070&rd=1
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MADE OF 100% HIGH QUALITY T-304 STAINLESS STEEL WITH BLACK CERAMIC COAT.
LIGHT WEIGHT DESIGN.
4-2-1 2 PIECES DESIGN. 3 INCHES COLLECTOR.
CNC MACHINE FLANGES . 3 STAGES POLISHED.
DEEPER TONE AND FASTER RESPONSES.
BOLT ON STOCK O2 SENSOR.
IN STOCK ITEM.READY TO SHIP! IF NOT MONEY BACK!!!

CONDITION: BRAND NEW IN BOX. NEVER TIRED TO INSTALL.

INSTALLATION: COME WITH GASKETS AND BOLTS.

APPLICATION : WILL FIT ON CHEVY HUGGER 283-305-357-350-400 SMALL BLOCK ENGINE

2. Bolt them on myself for free or have my buddy's son do it for a small fee.

3. Drive it with wide open headers to the exhaust shop to have them either tie it into the original exhaust and muffler with a Y-pipe of some sort they can make.. or order a couple flow masters and have them run pipe into those and out the back. It does look as though the cross member on the drivers side may prevent it from being tucked nicely on that side though.

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So my real questions are.. single of dual pipes to the back? I'm concerned with headers and no O2 sensor or CAT, would my motor actually get worse mileage without some of the factory equipment attached.  I was assuming without an O2 if might run worse.. and with an O2 and no converter, it might run too rich because of no CAT.  I really have no idea and was hoping someone on her would have experience in only adding header to a stock 59 or so motor.. and let me know if it actually ran less efficient or more efficient. I realize that when it runs better my foot will be in it more thus seeming less efficient but thats a whole other subject.

My goal here is to replace the original manifold because I have to and it will be somewhat more cost effective to do so.. but will I screw up the computer and whole goal of better breath-ability and perhaps better mpg.

any help is appreciated

Pat  

Gotta be careful with headers on the full size Chevys of your year, I've heard some stories about general fit headers not working on these trucks. I think the big install problem is on the driver's side where the steering box is, and some interference problems.

Your O2 sensor is on the driver's side, so you should be able to reuse that no problem.

Not running an O2 sensor on your motor is gonna kill your gas mileage, the TBI system has to have a functioning O2 sensor. The cat converter not being on the truck won't make a difference.

The best way o improve your breathability is to order a set of headers designed for your truck, get them installed, have an exhaust shop cut up a new Y-pipe that'll fit, and just run it through a big single pipe back to a large muffler. This is the course that'll present you with the least amount of trouble.