Exhaust mod

[Alan W]

I have a 2.8 and I am looking at a couple of options. I've done away with the underslung spare wheel which was very rusty and bought a nice clean secondhand one from a 3 series which I will now keep in the boot for easy access should I ever get a flat. with that out of the way I quite fancy the quad tailpipe look (two either side). There are two issues I need to consider, firstly is it easy to cut out the rear bumper o the O/S to mirror the existing exhaust cut out? Secondly, I was thinking of cutting the OEM exhaust just forward of the rear wheels and having a bespoke stainless system at the back end with two pipes and 2 boxes emerging as twin pipes either side? Any ideas on probable cost of this? Indeed, is it possible to joing stainless to normal steel? Am I better doing a cat back system? many thanks Alan

 

[Antm72]

Yeah i think someone has just had a quad system fitted on here they may be along shortly the garage that builds the exhaust does the cutting of the bumper if its the system you request.And yes most systems are cat back so steel to stainless.

 

[GazHyde]

The big issue is the battery box which makes it difficult to make a true dual back box system. A lot of the time they end up doing this, which gives the desired look without really doing much... This is the Eisenmann way of doing things.

 

[oldcarman]

Are pipes all functional equally @GazHyde? JIM

 

[GazHyde]

Yes Jim, but what use it actually is would be anyone's guess. I'd want it before the back box or feed from further up the system.

 

[Alan W]

The big issue is the battery box which makes it difficult to make a true dual back box system. A lot of the time they end up doing this, which gives the desired look without really doing much... This is the Eisenmann way of doing things.
View attachment 27229

Doh!!! I forgot about the battery tray, if my memory serves me right this is in the centre of the bootwell on the twin exhaust 'M' cars and l'm not keen on that Eisenman set up (and l bet it's bloomin expensive!!!)

 

[GazHyde]

Yeah, the battery box is what foiled my attempt at going quad when I got my exhaust done. That said, I will persevere and will have a proper quad system somehow. I may look to get the battery out of that well, and buy a smaller (and no doubt expensive) one which can sit somewhere else in the boot. Can then lose the battery holder, a have it welded up or something. Then would be looking to have one exhaust bank running to a separate back box.

Most of that is all hypothetical in my head at the moment of course! More thinking is required, but I'm sure it's doable.

 

[oldcarman]

Yes Jim, but what use it actually is would be anyone's guess. I'd want it before the back box or feed from further up the system.

Thanks Gaz, that's my thought also! I'm thinking running dual pipes with an equalizer pipe before the back boxes nearer to the cats. On V8's we paint the pipes and burn off the paint and where it stopped burning is where the cross pipe would go. Is it possible just to put a small resonator in closer to the cats instead of the boxes right at the rear bumper? JIM

 

[GazHyde]

It's really tight under there, even without the spare wheel and carrier. Probably could squeeze something small under there I suppose, I'd have to have another look.

To be honest, if you want a quad exhaust then I personally feel it's best to lose the battery box and build it properly!

 

[Dickymint]

or some nice side exit exhausts.... shorter exhaust would sound nice too

 

[GazHyde]

We've run mine without the whole back section on, basically nothing except the front cats... sounded really awesome, which is why I ended up with the very minimal setup I have now.

View: https://youtu.be/nkPPHBQjLWA

 

[oldcarman]

Yes @Dickymint I have considered that option also but like the dual cutouts sand pipes in the rear. Had side mounts on a van way back, awesome sound and will be putting a set on my 28 model A street rod once it go to pick it up! JIM

 

[5harp3y]

Battery could easily be relocated into the back of the boot next to the cd changer etc.

Get an agm battery which are smaller and lighter.

Then you can easily bin off the bulge and get a proper twin box system welded in