My experience with headers on my E39 is with SuperSprint. I've had them for ~11 years on the same car. I also added them to a 6cyl rice burner I ran for a few years.

My experience with NA on *anything* related to moving air- whether at intake or exhaust- is pretty much 'meh'. Manufacturers build in back pressure to make TQ before the motor really should. It sells cars 'cause folks think they're 'peppy'. I've surmised on my own experience that this is why many folks decide that NA intakes and exhaust are great for noise and something, but very little else on the dynos.

Similarly, headers and exhaust will raise the almighty HP numbers, but they will often rob that low end TQ. If you think ab a stock top and bottom end ability to produce power as being finite- which it is because the same internals can only make what they can make- this makes sense. Chips, intakes and exhaust really just move the power band around in the places that make us show higher numbers. They do this most often by providing space down (or up?) the power band when more air is moving through. Even the best enthusiast wants to see the #'s, so that's what we look for.

But if you take a close look at the before and after charts, you'll often see that the numbers peak at a different place than they did. Higher, yes. But most often later in the band- at higher RPM.

So I noticed that my SS headers made great power at around 3500-4000 RPM when there's lots of air to move out, I also noticed that it takes a little longer to actually *get* to that power- TQ moved later in the band as well. That's not to say that more isnt there- it's just that you might not catch up to that new 328 until you're rowing into 2nd- or maybe even 3rd. Not many stop light drags last a full 1320.

I made one early change to the intake on my NA V8 E39. It was an intake off a non-vanos V8. Yeah, I lost some low end TQ, but it showed up again with some new friends at around 3.5-4K. I lost early power in the band and moved it later. This made the 'peaks' higher. POOF! More power from a bolt on!

Enter FI. (Forced Induction)

Things got silly ab that same time once I added an SC. It may take a min to spin up. I might even tail at 60-120'. But once we get into 2nd gear and 4k or so, it's outright spooky. I did an onramp the other day in the SC'd E39, and the pit of my stomach felt like we'd just topped a high point on a country road. I was actually a little scared in my old(er) age.

Far from suggesting that the headers we're discussing here are equal to SS. They may be. That'd be fine. It'd be more than that. It'd be awesome, really.

More than that, this is a really long way of suggesting that the OP get himself some FI. Cause I've only seen one FI E39 iT and it was the sweetness of wagon function and complete balls to the wall motivation.

Also, it's kind of my hope to motivate anyone who wants headers to get them. They're super easy to install when the motor is out getting fitted to an SC.

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