do your own research

talk to an exhaust shop that does race setups

thats the easiest way instead of asking around here, most dont know much about quads and those that have them really only wanted them for the looks etc

 

Dual resonators, and dual high-flow cats installed after the cross-over (x-pipe preferably) and you will be fine. These engines really like some back pressure. Took us 4 different tries to make power on the 545i with our custom setup. The high-flow cat was key. For duals, the biggest issue is the lack of room on the passenger side, you are going to be very limited in muffler selection that will fit. I would be more concerned with how you are going to hang it without rattling.

 

What if your going the way where you replace the resonator with the center/dual magnaflow where the dual tips makes your quad. How would you set it up to not loose power.

 

it's not for us to convince you, it's for you to interpret what's given or what you find on your own....

most companies do give you piping diameter info with their systems, just need to make the time to contact vendors and/or manufacturers

it's obvious you have some knowledge about engineering, so continue your research...good luck...

 

The reason I asked here first was only because it seems that everyone is so easy to say quads will lose power so I figured there must be a large amount of evidence to support such a common claim. I figured by this time this thread would have been with a ton of comments but surprisingly it seems that this is not the case.

crmb,
Would you mind sharing more specifics about the exhaust system you developed including piping diameter and the manufacturers of the products you used. Also, maybe some pix if you don't mind. Thanks

 

great thread, wtb some more info as well.

 

OK...so the shop has my car today and they're doing a dual exhaust install with quad tips. It was an additional $140 for a before/after dyno that I didn't intend on spending, but I figured I'd take one for the team in an effort to get more facts. Feel free to buy me a beer after a meet-up if the data I gather today is of help to you.

First off, a little information on my vehicle: In the shop is a 2007 550i with 39,000 miles. The only modification thus far is an RPI Air Scoop which has also undergone the air inlet grate removal (https://5series.net/forums/topic/987...grate-removed/). Unsure if wheels make a difference with dyno results, but the vehicle is currently equiped with 20" Miro M6 replicas and Falken FK252's. Oh, vehicle also features stock air filter with carbon filter delete. The car is burning 92 Octane Chevron gas.

Now for the "Before" dyno results they gathered prior to installing the new exhaust. I can't find the "under hood" temperature on either of the two printouts they gave, me so I'll let you make your best guess of under hood temperature based on vehicle usage. The car was driven less roughly 5 miles to an Auto Sport shop near Market Street in Ballard from downtown Seattle after it had been sitting in a garage all night. Upon arriving at the shop, I let the car sit with the engine turned off for 60 minutes or more while I installed LCI tail lights (and also while the shop was preparing for the day/week).

Here is my vehicle sitting on the Mustang Dynamometer prior to the first pull:



Here are the results of the first pull (I'll type the results out below as well because the printout is a little hard to read):





Engine Torque (Ft-Lbs): Min-208 / Max-276 / Avg-253
Engine Power (HP): Min-88 / Max-256 / Avg-199
AFR (Ratio): Min-11.4 / Max-14.5 / Avg-12.9

I've never seen or had a car on a dyno before, so this was pretty fun for me.

I'll follow up with details of the installation and some videos. Stand by.

 

would either of these mufflers:
http://cgi.ebay.com/ebaymotors/Magna...Q5fAccessories


http://cgi.ebay.com/ebaymotors/Magna...Q5fAccessories

work with these tips:
http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

and the shop can do the rest

 

The parts they are installing are as follows:

1 Magnaflow Muffler part number 11385
2 Magnaflow Mufflers part number 10425

The shop has been guided to leave the Exhaust manifold(integrated cats) and two resonators alone. Everything after the resonators will be replaced. Each of the two resonators will run into one inlet of a dual-inlet, dual-outlet Muffler (11385) which contains an internal crossover pipe. Each outlet of the 11385 will run into one of the two 10425 Magnapacks, then out to the bumper where they will terminate with dual tips. The stock pipe diameter leaving the two resonators will be used throughout. All pipes are not stainless, but they will be using mandrel bends.

Here are a couple videos:

Pull1:

Pull2:

 

Awesome posting! Looking forward to seeing the results. Be sure to get some undercar pics if you can.