Yeah, I tried searching on tower for the 18TM header, but can't find it. Was trying to see if it was the same as the OS21TM header... not really sure how that would help...
Regardless, you may find it difficult to find a 18TM anything at a LHS. They are discontinued engines.
You know, now that I think about it, I ran a standard .15 header on my 18TM and it was fine. It was an associated header. Considering it was just your basic header, I don't see why it wouldn't fit the TZ as well. It won't work, because it's not bent right, but since it did work on my 18TM, then a 18TM header would fit a "standard" engine like the TZ I would think.
This is the one I used on the 18TM in my jato before I busted the crankcase:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXKGJ9&P=7
It fit the 18TM fine.
Not sure if you follow that logic... but basically, if you can find a 18TM header for the maxx, it should work. Make sure your not getting the revo header if your on ebay. There is a OS 18TM revo header and maxx header. They are shaped different for each rig.
Man... what a nightmarish search. The OS18TM-maxx version manual gives you the part number for the revo header. Searching the OS21TM for the revo on tower gives you the same header. So, the OS21TM maxx header would be the same as the 18TM maxx header.
This is the part number:
72103800
Found a reference on ebay from a guy that said he used the 18TM maxx header on his 18TZ in his t-maxx:
Ebay Listing
Item #: 290291664434