Another x-pipe exhaust question, but need technical details

[Professor]

Just got off the phone with my custom exhaust shop. They are a very high tech shop that work on some very custom vehicles. They said it would be $150 for the xpipe and install. Sounds very reasonable to me.

I'm getting so much different info on this site through the search function as to the placement of the xpipe. A few are saying they lost power and tq. because of improper placement. I definitely don't want that to happen.

If that is the case, then I want to know where the proper placement is. I know the shop i'm dealing with knows what they are doing but I'm betting they haven't done to much with X5's.

The video I saw of an install showed the x pipe placement more toward the front of the of the vehicle with the extention pipes coming off and going toward the back. is that proper placement?


Does anyone who has this done without issues have a pic?
Also, does this throw any CEL lights?
thanks
Matt

[JCL]

Originally Posted by Professor

If that is the case, then I want to know where the proper placement is. I know the shop i'm dealing with knows what they are doing but I'm betting they haven't done to much with X5's.

Process of trial and error. Small differences in location can make a big difference in performance.

[TwinsPoppa]

Originally Posted by JCL

Process of trial and error. Small differences in location can make a big difference in performance.

+1

I don't know how anybody could know definitively without trying different locations and testing on a dyno. I don't know of someone who has actually done that.

When I installed mine, I assumed there would be some loss. I prefer the nice sound over the performance hit. I had the x-pipe installed roughly in the same location as the resonator.

Also, it cost me $300 just for the install at a local Mineke/Midas. So, if you're going to do it, $150 sounds reasonable to me.

Good luck.

[Phr3d]

per JCL's comment, that was why I said read everything.. stainless is pretty precious to experiment with and one member who's name, unfortunately, escapes me said his towing was now HELL because of installing an X-pipe.

[TiAgX5]

In order for an X-pipe to work properly, the exhaust pulse phase at the x-pipe need to be the same as the pulse phase at the exhaust valve. Seeing as the BMW engineers went with unequal exhaust tube lengths from the cats to the resonator (left/right), the x-pipe will NEVER be as tuneable as one on a V8 that has equal length tubing upstream. With unequal tubing upstream of an X-pipe there will be certain RPM/load/throttle positions where the exhaust pulses are reaching the merge point at the exact same time (bad for performance).

[Papa13]

So, why wouldn't just replacing the res with straight pipes not work better?

[TwinsPoppa]

Originally Posted by Papa13

So, why wouldn't just replacing the res with straight pipes not work better?

IIRC, I think some people tried but it endend up being raspy/popping. I think the main function of the resonator is for sound tuning. With the xpipe sometimes (when cold) I get raspiness/popping.

For example, if just started and you tried to rev it the X sounds terrible. However, especially after a highway/high-RPM run, when you rev it the sound is awesome.

I would think it would sound terrible without the x-pipe.

As far as performance, don't know.

[TiAgX5]

For all around driving, that would be a better bet. If you were to set up your X for track only duties, you could find a spot in the system where it will scavenges in the upper RPM range at WOT.

[Professor]

TiAgX5.. I'm looking for a good sound w/o losing noticable power or throwing a CEL light. so should I go Xpipe or just delete the resonator? The main thing is i HATE cel lights on.

[Papa13]

Originally Posted by Professor

TiAgX5.. I'm looking for a good sound w/o losing noticable power or throwing a CEL light. so should I go Xpipe or just delete the resonator? The main thing is i HATE cel lights on.

No CEL light btw