Turbo Diesel Exhaust ?
 

Wondering if anyone has replaced the rear mufflers to high flow straight through mufflers? Especially if Dyno tested before and after. The factory mufflers are very quiet and being a backflow design look like they would be quite restrictive. At least the E70 model has the exhaust tip exit the rear and probably less restrictive.

I see here on this forum some have mounted fake tips to look like the V8's. I was thinking it may be possible to use a whole saw and cut a hole in the rear of the muffler and possibly Tig weld a tip or rivet one on like someone has done already but actually make it functional. It would depend on the design of the muffler on the inside and may require further drilling to improve flow. Leaving the original exhaust pipe. It could be a cheap way of improving the looks, performance, probably economy and sound.

Here are my tailpipes, fitted in place of the rear mufflers. Original hanging points were utilised by a local exhaust workshop tech. Makes a nice note and no noticeable soot on the rear of the car. Likely my colour helps mask it.

I didn't dyno before or after and can't say with 100% certainty that there is a performance gain, but they are several kilos lighter and are essentially a straight through pipe, with negligible back pressure. I bought the muffler/tailpipes from fastlanestyling.co.uk via eBay, though I don't believe they advertise there anymore.

How much were they? Performance wise it would make more of a difference with a tune,( more boost and fuel), which I plan on doing. I just bought the car.

This is the link, seems they are still trading.
BMW X5 (E53) DIESEL/PETROL STAINLESS STEEL EXHAUST BACK BOX TIP TAIL PIPE x2 | eBay
They do not post to Australia so I had to use a intermediate freight company. (forward2me.com) I paid them about $170 to have them receive and forward. All went without any hassles. I did not use the included clamps, the exhaust shop welded the mufflers to the existing pipe. I think I paid a further $200 to have them fitted, so not a particularly cheap exercise, but it achieved the look and sound I wanted.

Big thanks, this looks the go. I see in the description they are much shorter than factory to clear the diff? They shouldn't need to do this unless not offset in like factory. Factory size is 12inch wide x 12 long and 8 inch high. Do you the dimensions of these shiny ones are? Is it not too loud or droany?

It definitely has a powerful note to the exhaust, and also a slight drone at highway speeds but I don't regret doing the modification at all. They are less than half the size of the factory fitted mufflers.

Thanks for the pics and info. I see it is center in and this is why it needs to be shorter. I don't like drone and I can get custom mufflers made offset in and same size as factory but would cost a fair bit more.

About the DPF delete I doubt it would make more power unless tuned with more boost and fuel requiring more exhaust flow, and even then a ? A guy who works here had a turbo diesel Navara which was stock and he put a full 3 inch exhaust and deleted DPF and did a before and after dyno test and made zero difference. He later did a custom tune with more boost and fuel, which obviously made more power.

That small twin in twin out round piece under the car must be a resonator then. It makes sense as it is part of the exhaust with no flanges to easily replace it with or any sensors.

Exactly, and this is why the later diesel X5 (E70 and F15) all have straight out exhausts - they all have a DPF to capture the exhaust soot particles. The E53 has no DPF (unless fitted as an option before or after sale) and so the exhausts point down the eject soot particles directly to the road surface.

DPF vs no DPF could become an endless conversation (like an oil thread) but don't confuse a DPF with a catalytic converter - they are different beasts. The E53 3.0d does have a catalytic converter. The DPF retrofit kit appears to replace the standard cat.

The standard cat is of course only a single unit - there is only a single turbo on the E53 3.0d so that makes sense.... six cylinders into one turbo, with one outlet into one cat, into two outlet pipes to two mufflers.

It's not a resonator , it really is a catalytic converter, just not a 3-way and no sensors, I've seen one opened, they are as densely packed as any other cat, I'm amazed that the exhaust gasses manage to force their way through! :D