Single exhaust(and given the context of this thread I assume you are referring to the axle-back RPI) proved more gains than what, a factory exhaust? I think RPI makes great products, and its possible the small market of people willing to purchase dual exhausts for a non-M is a contributing factor for them deciding not to design and sell a dual exhaust, but if you are comparing a cat-back dual exhaust against the rpi axle-back, I'd like to see this proof.

 

Not to get into a pissing contest but you're actually wrong. Technically it is dual exhaust, its the tips that everyone references as quad exhaust.

I'm not sure of the main reason, but after creating a thread and west proving gains with his setup, I think people realized the myth that a "quad" or technically a dual exhaust would hinder performance, was false. For more information on this issue you can refer to the thread below and come to your own conclusion:

https://5series.net/forums/topic/985...t-and-fiction/

 

You got into a pissing contest. And I can piss further.

Even though technically it is a dual exhaust, 99% of the people on this forum refer to it as quad. So although it might technically be wrong, it prevents confusion and is much easier to say than "dual exhaust with quad tips"

A quad exhaust, or "dual exhaust with quad tips" if you must, can yield gains. That isn't the issue. The issue is however, that dual exhausts, or "single exhausts with dual tips if you must, yield higher gains.

 

Haha, I just want those who are entering this subject to understand in more depth the difference between quad and dual, and thanks for clarifying that. BTW is that the fountain in front of your house

All kidding aside, as for the RPI exhaust (or single-sided) yielding better results than a "quad" exhaust, well that's been proven wrong. Look though the thread and you'll see member west gained just as much power as RPI claims with their exhaust.

 

How much are you asking?

 

I for one don't trust the results of a mere 2 dyno sessions on a Mustang Dyno......

 

If that's the case, lets compare apples to apples and show me some customer dyno graphs of a 550i before and after with an RPI exhaust. Maybe I'm not searching enough but the only graphs I'm finding are two pulls from RPI.

 

This is a fair ask socale39, and all I was really looking for. I'm totally open-minded on the matter and would sure as shit replace my dual exhaust with an axle-back rpi if it produced more power, but I haven't seen evidence of this.

 

$600 plus shipping. I have the original ship packaging. Had it for less than a year, in "as good as new" condition.

 

Why are you selling it buddy? Have to be honest to 5 series member or else you get a beat down