XSeries-forum

I read that you fitted a Magnaflow cat back with x pipe and smaller back boxes. As I can't see that Magnaflow do a x pipe smaller than 2.25" and the standard pipe on the 4.6 is 50mm slightly under 2" did they up the pipe size from the cats back or did you have one made special? Thanks in anticipation.

Hi Henry
If I recall Raj has or had a 4.8is which I believe has 60mm system.
The 4.6 has 50mm on the drivers side 55mm on the other ?? Still it is a BMW after all.

Plus I do believe Raj had his system custom built but I would think he will be along to confirm that soon

Didn't know that, been under and measured pipe, never noticed one was bigger than the other, someone on here must know why. This will bug me now till I find out. Thanks Greydog for condemning me to crawling under the vehicle again this weekend to remeasure.

My pleasure Henry nice to know your weekend is planned now !! Idle hands and all that stuff.
I really don't see why there are different size pipes side to side and as an engineer it makes no sense to have different gas flows side to side, though it must have done to the guy who designed the engine.

I am in Lez's age group so I have a special tool for use on stuff under the car "Sons" younger, bendier and stronger. You should use yours.

The trick with different diameter pipes was used on ducati motorcycles to compensate for different pipe lengths from each cylinder possibly the same idea has been used here?

Top man IanP that could well be it.

How ever looking on realoem the 4.6 and 4.8 system look very similar just different sizes? Unless 60mm is optimum? Have to get the calculator out now to check the differences,

Easy boys.

Apologies for the delay.

Been a bit crazy busy with work and car LOL.

I've got a full custom Magnaflow system fitted by Raj@Profusion. So have full larger bore piping as I have the sports CATs then piping to the X pipe centre box and then piping to the small can boxes at the back.

He used some reducing pipes to change from the standard piping to the X pipe centre box and vice versa to drop the size again initially as I originally just went the X pipe box installed in the original system.

The system from either bank down through the CATs and then to the centre box are very different lengths and hence the slight difference in diameter widths I believe. It is to help keep the air flow through the centre box (and now X pipe box) similar flow rates.

Hope that helps,

Raj

Thanks for the answer, did the magnaflow system have/keep different size pipes or just go with the larger bore pipes. Do the 200 cell cats increase noise by much. I am looking for something that makes the hairs on my neck stand up when I floor it but isn't going to do my head in on a 300mile journey. I know i can have both cos my other car does as above but it took me a shit load of money and 3 different systems to find it, hence ali the questions

I've got larger pipework throughout with just an increaser to take the ID of the standard pipework to the new size.

The CATs do increase the noise level. Tbh mine sounds like an American muscle car and it gets a lot of attention but it's not intrusive or drony when driving.

Do absolutely love the sound.