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Discussion Starter #1


Lets face it, the quad exhausts are the single biggest giveaway on the M5, and for both security & on-the-road stealth reasons (nobody wants to race me thesedays), I've decided to perform the following exhaust conversion.. I think the furthest most have gone (from reading thru the forums) is debadging and maybe a 528i decal on the bootlid, but this takes things a step further (Remus will fabricate a special order tailpipe onto their rear box for an extra fee). My only real concern would be a probable increase in back pressure and resultant drain on power,. would the (more free-flowing?) aftermarket sports box help counteract this effect and maybe balance the equation of removing one complete side of the M5s rear exhaust section ?

Is there any real benefit in having 4-exhausts on the M5 anyway? I mean what impact (if any) would removing one muffler have on the engines output.. or could it be something to the order of -10 bhp ?. Considering the Alpina B10 makes a fairly healthy 375bhp from its 4.8l V8 with a 540i type exhaust (only with sports silencer)..
Any thoughts on this ? Anyone got a 520i badge lying around :2:
 

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I can't believe that will NOT affect power in a huge way. Run up and down a hill with one of your nostrils taped shut and see the difference!

Nice idea, though - and of course, I don't know anything for sure...
 

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interesting idea to say the least...while i like your creativity, you might want to look into a more free flowing exhaust muffler for this. Remus while a good company is not known as one the the higher flowing units on the market. If you were to keep the remus, i might suggest you use the Xpipe to get rid of the resonators
 

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Then it'd be even worse as you'll be at a 1/4 ratio rather than a 1/2!

Why not put a banana up 3 of the exhausts and see what it runs like - nice n scientific that.... :cheers:
 

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Not good for performance but an interesting idea. Now you need to get some square side view mirrors, a 520d badge and some cheap steel wheels with plastic hubcaps - nice! mmmmmm cherrsagai
 

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Discussion Starter #7
If you take the cross sectional diameter of an X-pipe (or indeed any section of stock exhaust behind the headers), its only really two pipes for much of the cars length which then branch into 4 (of equal diameter?) at the rear muffler section.. so if that's not considered somewhat of a bottleneck, then surely the 4-exhaust outlets are unnecessary ?

Any ideas on the travel distance of 3-ripe bananas when they shoot out the exhausts at 6000rpm into oncoming traffic (my calculator says 91.3mph and 3.2 mile range) :hihi:
 

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help me to understand :confused2

you want to remove these factory tuned quad pipes and replace them with what will surely be less performance (yet more stealthy) all because you are not getting enough suckers to race with on the streets?

hmmmmm
 

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Ashok Arora said:
He's Irish everyone ;)
So am I, and I think it is a great idea! :D You're gonna loose some performance, and I would be worried about what negative impact it would have on the engine. Be careful, but if you dont mind a few lost ponies I think that would be hysterical.
:cheers:
 

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If you really want to do something like this, it would be simpler and less damaging to performance to simply re-work the 4 exhaust tips so they point straight down like on the E39 540 and install the 540i rear valance.

If you want to be really stealthy, have only one pipe on the left extend down past the valance (as on the 540i) and cut the others flush with the line of sight along the bottom of the valance. This will maintain all (or almost all) of the design flow capacity, and will be a good deal easier to implement. The only downside is that you will need to wash the valance more often.

Regards, Dick Roberts
 

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Why not just go out and buy a used 540/6spd and supercharge it, or add NOS. Put a 525 badge on it, and go have fun.
 

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This system will surely hurt your hp as the restriction and evacuation of exhaust will become severly cramped. For maximum visual stealth, why not just buy the SuperSprint x-pipe and have some custom exhausts made to just hide or end them before they reach the bumper area? The best option for you is probably to rebadge, re mirror and leave the exhaust IMHO.
 

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I would buy a rear apron in the aftermarket that does not have openings for the exhausts. There are many sources for replica M5 rear aprons. If this is not satisfactory, then make some mods and fabricate it to your specs. There are companies that specialize in plastic and polymers that can do this for you. Then you take the already proven 4-pipe design and mod it. Cut off the tail pipes and weld on downward facing pipes, ala the E38 740i. That would be stealth. I do not see any problems with this reducing power.
 

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If you need to trade those mirrors with a set of square 540 mirrors, do let me know. In fact, I've got a bumper for you too! Do you need some style 32s? Yes, I've got you covered. You need to put in some authentic 540 sport seats too? No problem! Non-M side moulding? Yessuh you sir.

hehe
 

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Discussion Starter #18
So the general consensus is that bhp will be adversely affected.. well im gonna do it anyway, for the simple reason that its never been done before, a bold step into the abyss for m5board.com if you like, hell I'll probably even lie & declare it the best thing since Kentucky fried chicken that's not only good for your car, but good for your cholesterol too..

I've thought about the suggested 540i rear box conversion, but when you factor in the secondary muffler pointing upwards & associated bracket modifications \ welding etc. necessary (540i exhaust won't directly fit M5) then its a lot of work, and the possibility of the finished product ending up 'twice' as muted as a stock 540i doesn't really bare thinking about,. I'm guessing a full 5-litres of dispelled v8 gases could sound pretty mean and create a nice phroar out thru a (relatively) small sized remus \ supersprint \ sports exhaust outlet.. ,

The other (easy) option of modifying & bending the existing tailpipes downwards to conceal behind the rear bumper means the mod could be deemed irreversible by someone (not of a similar disposition to yours truly) upon resale, rather than showing them an existing unmolested M5 exhaust and pronouncing that it could be returned back to factory spec without any huge problem. I'm pretty sure that both stock mufflers are visible from he rear anyway.. but I suppose the whole idea here is that i'd like the exhaust to sound alittle more aggressive in tone & even downright nasty (by comparison to stock), yet still remaining a wolf in sheeps clothing visually.

I realise this makes absolutely no sense whatsoever to some people.. the same people who'd die for the badge & like to get noticed down the high street where a quadruplet of exhausts and an ///M power emblem adds maximum kudos and could increase their mating prowess & potential 10fold in a dog-eat-dog world full of inferior corvettes & upstart supras,. but i'd like to think I don't need anything to supplement to my charming personality & Gregory peck smile in succeeding with the ladies.. and hey, the look on some subaru owners faces when they get totally 0wn3d by a 520i will be priceless


jerbro, ur a real pal, how 'bout I swap you the v8 & limited slip diff too.. :haha:
 

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"I realise this makes absolutely no sense whatsoever to some people.. the same people who'd die for the badge & like to get noticed down the high street where a quadruplet of exhausts and an ///M power emblem adds maximum kudos and could increase their mating prowess & potential 10fold in a dog-eat-dog world full of inferior corvettes & upstart supras,."

:rolleyes:
 

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It's idea that's crossed my mind several times as well and it certainly would seem to be in the spirit of the E28 and E34 M5's. I'd say go for it! Either way, keep us posted on the progress of your project.

cherrsagai
 
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