Absurd exhaust system proposal for e53 X5 3.0i M54 // headers back for under $1,250?

[IkirisTheX5]

Originally Posted by bcredliner

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.)

[bcredliner]

Originally Posted by IkirisTheX5

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.)

I installed QTP oval remote controlled exhaust cutouts. I have made many mods to my engine and sorely needed less back pressure. My goal was performance but the sound is amazing.

I don't remember anyone here that has installed cutouts on a 3.0 but I am certain they can be. It would be necessary to cut a hole in the exhaust pipes and weld the cutouts in place. I had a shop do the cutting and welding and I ran the wires and installed the control in the center console. Removing the resonators is more work than the muffler and easier to correct if you don't like the sound.

Location of O2 sensors. https://www.pelicanparts.com/BMW/tec...eplacement.htm

X pipe would be after the cutouts and before the resonators if you keep them. Most believe the X pipe is best. Note that the X pipe tends to produce a lower tone and the Y pipe tends to make it sound raspier and higher pitched. They both scavenge the exhaust, the X a little more than the Y.

When I do mods I do a value equation. What do I gain in performance per dollar spent? I suggest you calculate the costs of options you would like to consider and see what wins based on value. In the case of exhaust changes the gain won't be much whatever you do so the sound you want is part of the value.

The low restriction filter helps some. More if it draws colder air from outside the engine bay. Cooler air is more dense, engines love it. Any gain would be at higher RPMs when there is a greater demand for air. So after 3500 is likely when you would benefit the most. The key to getting the most out of low restriction filters is once you have made the change look for the next restriction before the air gets to the engine. As an example, Dinan is a complete system. Airbox to get only air from outside, the low restriction filter, a larger air intake tube, a larger diameter MAF and throttle body. That eliminates the air volume being throttled down anywhere. Coupled with the Dinan exhaust assures you are getting the max gain. Dinan also offered a matched tune.