They are really pushing the 2 and now 3 chamber pipes do to noise. A lot of the sanction racing are getting real sticky about this. More so over seas! I use to run this pipe and it worked quite well.
http://www3.towerhobbies.com/cgi-bin...?&I=LXBMH0&P=7
I now have an OS pipe, which OS recommend for their TZ I am running but it has been discontinued. But it is a 2-chamber pipe. Matter of fact I have not run my MT since I installed it. Now that the main racing season is over for 2007 I need to play around with my MT as it has been months.