New Group Buy - BB ByPass System 3.2M 3.0Etc - NEW VIDS PG 8

M@r said:
{"]No didn't get the sports cats fitted in the end, turns out the problem wasn't with my Cats it was with my manifold. so all standard M exhaust except these bypass pipes
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Makes me want them even more then :thumbsup:
 
mmm-five said:
M@r said:
{"]No didn't get the sports cats fitted in the end, turns out the problem wasn't with my Cats it was with my manifold. so all standard M exhaust except these bypass pipes
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Makes me want them even more then :thumbsup:
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Do it Do it Do it!! :lol: (starsky and hutch style)

Shooter have you got an M this may make a difference if your a little worried cannot be sure form your avatar :?
 
Paza3 said:
Shooter have you got an M this may make a difference if your a little worried cannot be sure for your advatar :?
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Didn't change my avatar yet, but yes, i've got an M roadster since the end of february. :wink:
 
tomscott said:
Oh rite, I see. I interpreted the images wrong. Sounds good!! So is the fitting basically available at any reputable exhaust fitter once the pipes have been purchased?
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Anyone for Kwikfit. :-)
 
Sounds great... i'm really glad this has worked out for you. Its been a bit nerve racking having people cut and weld tubes to their exhaust based on my post, just in case someone hates the sound when it's done, but having lived with the sound for a while now, its still great fun and never annoying like many exhausts I have lived with. It also makes it adjustable... if you want less noise, just use smaller pipes... for more noise, use larger pipes.


Of course the other option open to people is using exhaust valves like these, to give total control over sound and flow from the cockpit:

http://www.quicktimeperformance.com
 
Just read through this thread,

Pixelloftt- fantastic idea, :thumbsup:

M@r]{ - big thank you for the before and after vids (and sacfiricng your pristine camera! :o :cry: )- very nice comparrison - did you go for 3/4" pipe? One on each back box?

Pazza - well done for the drawing schematic. :thumbsup:

I'm pretty sure Im going to give this ago.

Am I right in thinking this is reversible too? - I.e. remove the pipes and close the holes or is that not possible once welded?
 
Yes I used one 3/4inch pipe per side :thumbsup: And it would be reversible just by removing the pipes and welding up the holes :thumbsup:
 
massive interest in this for 3/4" pipes for a z4m!awesome thread-how have i not heard of this mod before??
 
Ok did a proper track side style DB test on this today (on request) That means approx 1.5 m from the exhaust at an angle of about 45 degrees. Then hold the car at 3/4 max revs. So based on a 7.5k limit I held it at about 5600revs.

If I'm honest I'm surprised at the results. I was expecting it to be a lot higher than that. It may be because we have two exits so rather than having the meter directly behind the pipes its at an angle to both? But I'm no expert. Its making me question my DB meter now though.

Anyway here is the video

 
M@r said:
{"]Ok did a proper track side style DB test on this today (on request) That means approx 1.5 m from the exhaust at an angle of about 45 degrees. Then hold the car at 3/4 max revs. So based on a 7.5k limit I held it at about 5600revs.
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Z4M rev limit is 8000rpm, so you'll need to go to 6000rpm to measure it properly :poke:

Normal track days measurement is at 3/4 revs from 0.5m @ 45ยบ from tip - but they only measure one set of pipes.
 
Screw that, I didn't like holding it that high :) Well the main thing is it shows its not stupid high and will be below 95db, so will be fine on the strictest of track days :thumbsup:
 
M@r said:
{"]Screw that, I didn't like holding it that high :) Well the main thing is it shows its not stupid high and will be below 95db, so will be fine on the strictest of track days :thumbsup:
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I hate the sound of a revving engine in a stationary car too!

The trackday sound checks are almost as bad as rolling road days where you expect your engine to go bang at any minute (none of mine ever have though).

The problem with the pops & bangs is that they'll be the loudest/peak points, but the baseline may be 5-10dBa lower. Some of the track ones 'normalise' the reading over a second or to to limit these aberrant readings.

Donington/Silverstone regularly have 105dBa or unsilenced days. The higher the limit, the more costly the day, as they're only allowed to run a certain amount of 'loud' days, so they're at a premium.
 
Booner said:
I want to do this mod, but I have the Eisenmann backboxs. Can I still do this mod?
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Can't see any reason why not, as long as there is enough room either side of the box to drill a 3/4in hole and weld it.
 
:headbang: :headbang: Sorry guys went to the garage today , and they thought it was the same as Nick's on the M Boxes that they just bolt off, on the si system this is not the case and there are no breaks.......

Anyway cut a long story short we have had to rearrange as I only had 2 hours this morning and they did not have time to do it all :headbang: .

So should be done next Saturday now... worse case week after :(

Well disapointed , p.s if not an M put another 40 quid on the price for take the exhaust off and refitting as all the brackets etc all the way to the front of the car need to be removed etc ........ alll in the name of Zedding :)
 
M@r said:
{"]Screw that, I didn't like holding it that high :) Well the main thing is it shows its not stupid high and will be below 95db, so will be fine on the strictest of track days :thumbsup:
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Thank you very very much for the test. Now that i'm reassured, i'll get some of those magic pipes... :D
 
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