I have two brand new sets of Cmi e-top headers. Which I am curious if they can be modified to work on my 496 HO's? I have never had the manifolds off of these engines, so I do not have any knowledge to the changes on the bolt pattern etc. I plan on pulling the engines this winter to detail the bilge, so that would be the perfect time to upgrade the exhaust.

You will have to fabricate oil filter brackets and may have to fab an oil line.

Depending on the CMI's if they have the correct exhaust manifold temp sender you are good to go. If not, someone will have to weld them in too.

You can jumper wire the water temp sensor that goes in the manifold/header.

Dont bother, wont give you any performance gains.

Isn't one of the manifold bolt holes slightly different than a normal BBC too? Thought I've read that somewhere in the past.

The 496 8.1 and 454/502 base are the same exhaust bolt pattern. It's the stock 525 EFI heads with the different pattern. As to power gains, your looking at 20-25 propshaft HP gain. Roughly 1-2 mph IF propped right.

How do you do that? I have tried and was unsuccessful. (several times)

I think the ECU reads an actual temp. They arent go/no go.

when testing other exhaust on the dyno... I just used a paper clip that was cut & used as a jumper. the sensor in the header sends a signal to the computer when it over heats.. I don't know the exact temp, but it goes into guardian mode. What year/model # 496 do you have?