BTW, when I got my MTECH rear, here are other part numbers I got with it. I don't recall using all these parts however but it's good to have just in case. They were based on looking at the MTECH kit installation instructions:

51717066229 Pillars rocker and floor - Exterior trim - Rocker molding - Pin Pin Back - Sedan 2004 - 2009 16 $0.26 $4.16
51717066226 Pillars rocker and floor - Exterior trim - Rocker molding - Spacer Spacer Back - Sedan 2004 - 2009 16 $0.51 $8.16
51717066223 Pillars rocker and floor - Exterior trim - Rocker molding - Upper retainer Upper retainer Back - Sedan 2004 - 2009 16 $0.92 $14.72
51127896615 MOUNT 1 $27.81 $27.81
51127896616 MOUNT 1 $27.81 $27.81
51127897144 GUIDE 1 $21.82 $21.82
51127004445 PLUG 6 $0.26 $1.56
07146979392 BODY NUT 10 $0.17 $1.70
07129904150 Front lamps - Fog lamps - Fog lamp - Nut Nut Back - 2004-07 2004 - 2007 10 $0.17 $1.70
51717896625 Rear body and floor - Rear body - Underbody shield - Battery tray Battery tray - Sedan 2004 - 2005 1 $26.70 $26.70


Parts were bought from onlinebmwparts.com


I think the rocker molding parts are for the sideskirts so check on the part numbers to make sure.

 

Flapping diffuser resolved!

Total cost was about $100 + $12 shipping (from Gary of Newport BMW) for two support brackets, one central support guide, and all nuts/bolts/etc. The diffuser is now well-secured, thanks Balbs for the info. I highly recommend this for anyone considering buying an aftermarket MTech rear bumper.

Total installation time was about about 2 hours (I did it myself).

Although I ordered all recommended parts, I found that I didn't need several pieces (might have saved me $20). I will list only the critical parts below:

2 rear support pieces (left/right) @ $23.25 each (46.50 total)
51 12 7 896 615
51 12 7 896 616

1 central support guide @ $19.60
51 12 7 897 144

6 push-button plugs @ 0.25 cents each ($1.50 total).
? not sure 51-12--7-0004-445?
- 2 for the diffuser to the central support guide
- 2 for the wheel moulding to side supports
- 2 for secure bottom of right/left bumper face to side supports.

6 hex head screws (w/ washer) @ $1.50 each ($9 total)
51 11 7 070 199
- 3 on both left AND right to secure the support trim.

6 torx screws (t-20) (w/ washer) @ 0.39 each @ ($2.34 total)
07 14 7 075 519
- 3 on both left AND right to secure the bumper face, through the wheel well to the support trim.

3 body nut @ 0.13 each ($0.39 total).
07 14 6 949 379
- 3 to secure the central guide support to the rear of the car

So, I could have spent only 79.33 (not including shipping) for all these parts.

 

Awesome dude. Looking at your prices looks like it went down. Zip-tie delete FTW!!

 

Do we need these on top of ordering the MTech rear bumper?

 

if you are ordering a replica Mtech, then yes if you want it really secure. like the thread says there may be some flapping and use of zip ties without these parts. lol! a full OEM Mtech kit will have all these parts already included.

 

So it doesn't matter if its a pre-LCI or LCI e60?
Those brackets need to be ordered no matter which model?
What about an aftermarket Mtech front bumper and sideskirts, any additional mounting hardwear needed?

 

for the rear i don't think it matters if it's pre-LCI or LCI.
as the thread says, you can install without the extra brackets if you want to use zip ties to secure it. the brackets will make it more secure and eliminate any flapping from the diffusor.
sideskirts do not need any additional hardware.
the front just needs the brake air ducts, and others say maybe the mtech foam bumper pads, but i just got the ducts.

 

Okay thank you so much for the info. I'll post some pictures after the kit is installed along with other mods im doing.

 

did you replace the front bumper also? what brand?

 

I had a different bumper - OEM M5 rear. Which I think was more of an issue since the M5 has the plastic underbody panel that doesn't fit on our cars since we have spare tires. What I did was get some thin galvanized steel roofing straps from Home Depot, and using very small self tapping screws I ran the straps from the center of the bumper to the spare tire well. Never had an issue with flapping.