This will be a two part post so any feedback on either topic is appreciated.

1. First, I have a 2010 535i and I want to do a quad exhaust set-up. I've heard both stories that doing a quad exhaust on a non M5 will reduce power or it won't. I want hard evidence though! Most of the guys with the quad set-ups love them and report no major power loss but has anyone dyno'd with a quad set-up or any pros out there that can give a good explanation? I'm assuming that this all has to do with the back pressure or something, so wouldn't it be safe to say that by just running the proper size piping there would be no loss of power? I'm planning on getting down pipes too. I don't know if that means anything. I don't know, I'm not an expert but that's why I'm asking. Also, I know there are companies out there that have made a quad exhaust set-up but these are not going to do it for me. They're just not loud enough lol so if i do go with quads it will be custom. If the horsepower loss is that significant, I will drop the idea and stick with a dual set-up and most likely go with the M-Tech rear. Please if anyone has had any experience with this or anything to enlighten me on my best options, share please. Here's a thread that pretty much sold me on the idea though. Check it out. What do you think? TIA
Quad Exhaust


2. Ok guys, I've searched everywhere and cannot find this bumper anywhere. Is it just a regular M-tech bumper modified to fit with the quad diffuser or is it a whole different bumper? I'm still not completely sold on it, but if I do end up running a quad exhaust set-up, this is an alternative from the M5 rear I've been thinking about.

 

Thats an OEM m tech bumper and they sell those Diffusers. Seen some on eBay.

 

I have one of those diffusers from eBay. Fitment is "eh". I'd look at the one from JL Motoring, maybe it fits better.

 

Here's the perfect thread for you to read though, it's quite a lengthy read but a whole lot of info regarding dual exhaust w quad tips. This thread is what inspired me to go out and have this done with confidence. This is why I love this forum


https://5series.net/forums/topic/985...1#entry1171669

 

Yes I've seen the diffusers everywhere too. So it's just a direct replacement to OEM? No cutting or anything. OEM M-Tech only has an exhaust cut-out on the left side...In this link it looks like with the diffuser off it is different than OEM??My link

 

Thanks for the input. I've never heard of JL Motoring, I'll check them out.

 

Thanks a lot. This does look like a good read. I'll check it out and get back to you.

 

It should be a direct fit. It should use the OEM clips that the OEM diffuser uses to attach to the bumper. Looking under the 550, theres a black piece that covers where the M5 has its second muffler. I imagine you have to remove that, and thats it. I dont think theres anything there.

 

My diffuser came with bolts that thread into the diffuser itself from the backside of the bumper. You can't use the 4 stock screws and speed nuts. The only way to get those 4 bolts in for mine is to remove the bumper- the carbon fiber doesn't flex enough to do it while on the car. I've only got the 2 corner screws and two plastic rivets on the bottom middle of mine keeping the thing in place until I feel like not being lazy. lol

Arctic is correct on the passenger side. There is a black plastic piece that you unbolt to make room for piping on that side.

 

Thanks a lot guys for your time. It all makes sense now lol It's such a tough decision between M5 rear and MTech though(for me at least). But thank you again, answered my question