Since I hadn't seen it done yet on an N62 engine on Xoutpost, here's some info for you all. So after a year of debating on whether this was worth doing, the mod bug bit me and I decided to pony up the cash and do it. I didn't do it for any performance reasons; I did it because I love the sound and look. First, you need the exhaust pipes:
18107529454 - Passenger side exhaust (Right)
18107529453 - Driver side exhaust (Left)
After picking up the parts and looking at it, there are a couple things you'll notice. First, the pipes are wider than stock 4.4i pipes. I measured the new pipes to be 2.25 inches in diameter. I know a few on the forum who have installed X-pipes have said their 4.4i pipes are also 2.25 inches, but I measured them to be only 2 inches. Second, the pipe flanges that bolt up to the resonator are also slightly bigger due to the increased pipe size. Third, and most importantly, the exhaust flange alignment to the resonator is also different. See
RED reference lines.
What does this all mean? Sorry guys, not a straight plug-n-play mod here. This mod requires cutting and welding.
Also, when lined up side-by-side, both pipes share the same pipe bends as the 4.4i and fit directly on the existing rubber hangers. After a test fit, I noticed a problem where the driver side pipe was short by 1.75 inches.
So in the end, I decided this was much more work than I could do myself and went to a local exhaust shop.
Here are the 4.4i pipes are being removed - Two x 13mm nut and 14mm spring loaded bolts hold the flanges of the resonator and exhaust together. An pneumatic wrench + a torch to heat up the bolts made quick work of loosening them.
You'll clearly notice here how the flanges line up on the 4.4 resonator/pipes.
Once removed, the next step was to cut off the 4.4i flanges
Then the 4.8is flanges were cut off
Test fitting the passenger side since it has to be installed first
The previously cut off 4.4i exhaust flange is re-bolted onto the resonator and then tacked onto the pipe
Unbolted the flange and pipe again to complete welding all around
Then reinstalled. Here's how the passenger side looked underneath fully welded and installed
For the driver side, they cut a 1.5 - 2 inch length of steel pipe to use as an extension since it was short by 1.75" in my measurement. Then they test fitted, aligned and bolted in the flange, tacked into place, and welded it completely.
Here's how it looked when the welding was complete
After fully installing the flanges, they made sure the exhaust tips were correctly aligned using a level and feeling the gaps around the tips and bumper. To fine tune the alignment, they broke out a big wrench and made some slight bends in the exhaust hanger arms.
All done. Excellent job in only 1 hour.
So for the most important part...what does it sound like? On startup at the exhaust shop, it growled deep and loud like a bear waking up from hibernation. The idle hummed with a bassy gurgle found on the 4.8is. No adverse change in interior sound but a nice, slightly deeper rumble in the background. I would put the sound somewhere between the stock 4.4i and 4.8is exhaust sounds. As the weather's warmed up, the sound has gotten deeper. So far, I'm really happy with it. I have before and after videos, but I'll post them later.