Not sure what "bolt on hooks" are but here is a post showing how NCX's X-pipe has the supports welded onto it so the system has some support:

http://www.xoutpost.com/x5-e53-forum/...haust-mod.html

I haven't been under my X in a while but I do not think the angle of the pipe going into the X-pipe is much of an issue. There should be enough pipe left after the resonator is removed to weld on the X-pipe.

I think the other guys who have had it done have had the supports welded on and the price was around $100 - $150.

To answer Bob's question the X-pipe is a bit quieter then the striaght pipes.

i'm going to do this mod for 3.0 maybe with the header too,but first i have to find the shop around where i live.(detroit)

exactly, dont want it TOO loud as straight pipes will sound.
as far as angle of the pipe goes, once resonator is removed there's barely 1" of straight pipe before it makes almost 90 degree angle.
kind of short, pic that was referenced is probably from 3.0 not from 4.4

I have this mod on my 2001 4.4 and I removed the resonator as well. I like the sound; however, during hard acceleration there is annoying sound as well. It is hard to describe but it sounds like a clicking sound. It has more to do with the resonator delete but I placed the X-Pipe in place of the resonator for a nice low exhaust tone. It really is not that loud and I'm not in the gas flooring it all the time so I live with it the way it is now because 95% of the time the X5 sounds sweet.

Nope... pic referenced is from NCX's 4.6is. Also the x-pipe isn't much louder, but adds a deeper exhaust note.
Sounds great on my 4.4i with Remus. BTW I don't have any type of weird sound or clicking going on... just sounds
awesome! My indy shop did roughly the same install job on my X. Here is NCX's x-pipe installed: :thumbup:
http://xoutpost.com/gallery/files/2/5/finished_xpip.jpg

zerochief, on your pic, pipe thats on the top-left, does it go into 90 degree turn? (beyond the pic area on the left side)

Yes it does.
 

See these pics for the angle of the OEM pipe before the xpipe.

http://xoutpost.com/gallery/files/2/5/test_fit_xpip.jpg
http://xoutpost.com/gallery/files/2/5/weld_hangers.jpg

alexz, installing the x-pipe s/b no problem for any reputable muffler shop in your area. :thumbup:

Sorry, does the X pipe make the X5 sound better or just improve the performance and efficiency? Does anybody know where i can get one in Australia?

http://magnaflow.performance-curve.c...ROD&ProdID=421

Above is the link to where I bought mine a couple months ago. I'd imagine they'd ship abroad.
I didn't notice any perfomance gain, but it really sounds great!