A long time desire has been to get the Z4 to quad pipes as they just look ‘right’ and probably the last major project I want to do on bodywork.
I grabbed a ///M rear facelift style bumper cover off ebay, so have that and also have a pair of new genuine ///M backboxes in the garage, that I could also use in the project.
Some Basics:
I prefer to keep my prefacelift rear lights if possible. I just like them.
I don’t want to gain or lose performance, nor get a noisy exhaust. I get enough trouble from Mrs CJ for the X5 with it’s Hamann quad pipe cat back system that makes babies cry and me smile everytime it starts up
It should be functional as a quad system, so no dummy tips and all must vent to look right.
The research is almost done and I see several options and am interested in input and comment before spending and setting to work with the surgeons knife and Birmingham screwdriver (aka hammer).
In effect the project breaks down 2 separate aspects that can work in any combination - bodywork and exhaust.
I have 2 options for the bodywork:
1) Swap the ///M bumper cover onto mine and have a bodyshop reprofile it to fit the original lights. Lot of profiling, spraying and always a risk of repair cracks emerging in years to come.
This sort of idea - the bumper profiles to the lower edge of the lights:
2) Fit the OEM facelift diffuser to my existing bumper (no idea if it will fit, bit it WILL. I could and would make it) This saves messing with profiling for the lights and avoids a £200 bumper respray. Would need an extra hole cutting for the right side tips. Costs £300 though.
This, but of course on the earlier bumper cover:
Next 2 options for the exhaust:
1) Go for the side T off the existing backbox
Done by FemmeT and others and is in reality a simple conversion, albeit not liked by the custom exhausts shops I’ve spoken to.
A sort of DIY of this style done by many aftermarket suppliers:
2) Fit a split pipe from the centre box /resonator back and incorporate the ///M boxes.
Original rear section of mine
M mid section – almost identical at the kidney and perfect point to ‘T’ into using custom pipe
Rear boxes that would connect to my ‘resonator’ with custom pipes to the back boxes.
Uses OEM backboxes, but needs the battery locating in the boot or perhaps a much smaller battery somewhere – (read expensive with first quote of £500 just to move the box and battery, but I could likely do that myself having taken a good look) for a few quid and parts from for the ///M roadster battery set up from a breaker / dealers, plate over the old void. This is a big consideration on cost, luggage space, but it’s a beautiful solution from a look, performance and gut feeling.
So what do we think of the 4 possible combinations?
Move the battery and use ///M boxes or the cheaper T pipe option?
Go OEM rear ///M bumper cover, or the diffuser?
I’m currently leaning towards move the battery, fit a diffuser on the OEM bumper and use a true twin back box and quad tip set up. It would be unique, which I sort of like.
I grabbed a ///M rear facelift style bumper cover off ebay, so have that and also have a pair of new genuine ///M backboxes in the garage, that I could also use in the project.
Some Basics:
I prefer to keep my prefacelift rear lights if possible. I just like them.
I don’t want to gain or lose performance, nor get a noisy exhaust. I get enough trouble from Mrs CJ for the X5 with it’s Hamann quad pipe cat back system that makes babies cry and me smile everytime it starts up
It should be functional as a quad system, so no dummy tips and all must vent to look right.
The research is almost done and I see several options and am interested in input and comment before spending and setting to work with the surgeons knife and Birmingham screwdriver (aka hammer).
In effect the project breaks down 2 separate aspects that can work in any combination - bodywork and exhaust.
I have 2 options for the bodywork:
1) Swap the ///M bumper cover onto mine and have a bodyshop reprofile it to fit the original lights. Lot of profiling, spraying and always a risk of repair cracks emerging in years to come.
This sort of idea - the bumper profiles to the lower edge of the lights:
2) Fit the OEM facelift diffuser to my existing bumper (no idea if it will fit, bit it WILL. I could and would make it) This saves messing with profiling for the lights and avoids a £200 bumper respray. Would need an extra hole cutting for the right side tips. Costs £300 though.
This, but of course on the earlier bumper cover:
Next 2 options for the exhaust:
1) Go for the side T off the existing backbox
Done by FemmeT and others and is in reality a simple conversion, albeit not liked by the custom exhausts shops I’ve spoken to.
A sort of DIY of this style done by many aftermarket suppliers:
2) Fit a split pipe from the centre box /resonator back and incorporate the ///M boxes.
Original rear section of mine
M mid section – almost identical at the kidney and perfect point to ‘T’ into using custom pipe
Rear boxes that would connect to my ‘resonator’ with custom pipes to the back boxes.
Uses OEM backboxes, but needs the battery locating in the boot or perhaps a much smaller battery somewhere – (read expensive with first quote of £500 just to move the box and battery, but I could likely do that myself having taken a good look) for a few quid and parts from for the ///M roadster battery set up from a breaker / dealers, plate over the old void. This is a big consideration on cost, luggage space, but it’s a beautiful solution from a look, performance and gut feeling.
So what do we think of the 4 possible combinations?
Move the battery and use ///M boxes or the cheaper T pipe option?
Go OEM rear ///M bumper cover, or the diffuser?
I’m currently leaning towards move the battery, fit a diffuser on the OEM bumper and use a true twin back box and quad tip set up. It would be unique, which I sort of like.
