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Old 08-30-2021, 03:21 PM
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IkirisTheX5 IkirisTheX5 is offline
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Location: Texas
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Originally Posted by bcredliner View Post
It is possible that the length of headers can decrease torque. It largely depends the overall length and if they are equal length. Torque is what gets you going. Be sure headers for the 3.0 do not reduce torque. Claims of increase HP and TQ by owners are hardly ever backed up by dyno runs, the butt dyno means nothing.

I wouldn't add headers unless they were a name brand that lists gains. It doesn't mean the claims will be accurate but that is why they build headers. The gain with the right exhaust isn't much. As an example the Dinan free flow muffler for a 3.0, when it was available, increased the HP by 5 at 6500 RPMs and TQ 4 also at 6500 RPMs.

If you are after better sound I would install electric cutoffs equal length from the exhaust manifolds and past the first O2 sensor. The cutoffs should increase performance but I don't know how much. Based on Dinan only offering the muffler for the 3.0, a low restriction muffler should be beneficial.

Before modifying the 3.0 exhaust I think I would start with letting more and cooler air in as happens with a cold air box. Once you have more air going in letting more exhaust out should help a little more. If you then get it tuned to match up with the changes you should get yet a little more improvement.

In short, I would add an air box, a low restriction muffler and electric cutouts and call it a day. Both the muffler and air box will improve the sound of the engine and cutouts are great fun if nothing else.
I like the way you think and electric exhaust cutouts are about as absurd as any exhaust mod I could think of. Do you happen to have them on yours or know anyone with a 3.0 X5 who has had them installed?

I’m a little confused on what your recommended placement is… you said: “install electric cutoffs equal length from the exhaust manifolds and past the first O2 sensor” —— I think it’s the O2 sensor part that’s tripping me up; aren’t those in the manifold? Maybe a better question to ask is if I delete the resonator at the same time should these come before the x-pipe?

In terms of performance, it’s funny but I couldn’t find much in way of definitive numbers for hp gains with cutouts, besides some guy with a 500hp Challenger who dyno tested it with cutouts open and closed and he reports a +10hp gain with them open.

I already have a “short ram induction” exposed cone style filter installed on her. It’s not one of the fancy aFe or Dinan ones but I’m sure it gets the job done all the same. I didn’t notice a particular increase in power from it until about 3500 rpm but that could also be just wishful thinking on my part. Sounds nice though.

Anyhow, thanks for the cutout advice. I am seriously considering it now! (Would just love to find another X5 owner who has already done it though.)
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