Hi Tomwac,I have been taking my time with my exhaust project for my 3.0D but
I am pending to go for the 4.4 silencers and trims.Here in Portugal the silencers
cost 786 euros and the slide-on trims a further 243 euros=total 1029 euros.Cheaper
than aftermarket systems and you get to keep the oem look.I have looked at other
alternatives like universal stainless steel silencers but the X5 silencer is very short
and not a lot of room to then fit the end trims,which is the reason why I have been
looking at the possibility of fitting the 4.4 oo 4.6 silencer/trims.The 3.0D pipe diametre is 51mm,the 4.6 has 57mm which will improve you back pressure.I dont know what the
diametre of the 4.4???Maybe you could let us know!Make sure that you weld all joints
in stainless steel to match the oem pipe material.
I look forward to learn if you still dont get any soot coming out with the 4.4 pipes!
What "tuneup " do you have?Is it a box or reprogrammed?What make?How much?Thanks

Well, I'm also after the OEM look...I bought the 4.4 mufflers cheaply. I'll measure the pipe diameter tonight and will post it, but I guess it's the same as the 4.6. The tuning is programmed, no powerbox. They custom program for each vehicle to obtain the best results. And it works, as my 0-100 time improved to about 8.7 seconds :) which is not bad for a truck this size. I'll keep you posted about the soot when the pipes are installed.

The outer diameter of the pipe is 50mm. Hmmm....

50mm!!!!I just re-measured my 3.0D pipe diametre from the middle of the car up to the rear silencer and measurements vary between 49.5 and 50.5mm!So,not 51mm as I first measured!I didnt personally measure the pipe diametre of the 4.6is(57mm)and I assume it is correct!Perhaps someone in the forum with a 4.6is can verefy this please!!!!Dont want to go off-topic,but wouldnt the 4.4 benefit from the larger diametre pipe of the 4.6is???The 4.4 would get more bass and a deeper growl!
Tomwac,are you still going to fit the 4.4 silencers next Tuesday?The pipe diametre maybe the same as the Diesel but you should still see gains as 4.4 silencers are straight through and less restrictive.
Still,I cant stop thinking,if 4.6is 57mm and 4.4 50mm,the first performance mod on the 4.4 should be 4.6is exhaust!Whats the point of buying aftermarket exhaust systems if
pipe diametre is the same.Supersprint are one exception,they do a 54mm system for the 3.0D,its a shame that its much more expensive than oem and they have their name engraved on the tip!