Exhaust Manifold
 

Has anybody tried a header in place of the stock manifold?

Does anybody have any experienced opinion (vs knee-jerk response) as to whether it would be likely to improve power or economy? Increase overall exhaust pipe diameter also?

It is generally considered good to increase flow, and I have heard moreso with diesels, but would it be measurable on these motors? Keep in mind that even a 2hp gain is significant as a percentage of total.

(240D)

Absolutely will make greater efficiency + power. Especially with port work, but you'd need to take the head off for that.

Here's a guy who did a lot of modding to a 617 including headers / larger pipe and claims 123hp (crank?) from NA OM617 (35hp increase)

http://www.pointedthree.com/disc/forums/showthread.php?tid=1689&start=21&posts=40

They don’t do a lot unless you’re heavy on the throttle.

Sixto
98 E320s sedan and wagon

On a 240 you might eleminate the center or rear muffler. If you can stand the extra noise you might be able to notice an increase in fuel economy. I doubt porting and making a header would result in measurable positive results.

Depends on the engine. Would be a major redesign on my turbo diesels. Most who fab start with a baseplate - ebay for many engines.