As far as the Tsais rear pipe I have only talked to one person that runs it and they liked it. My main concern with this pipe is what happens if you do a jump and land on the back of the truck? This pipe can be gotten here in the US for $50 before shipping.
http://rchub.com/Merchant2/merchant....tegory_Code=ND
The THS pipe I have talked to quite a few people running it and they all like it. I was running a pairs ribbed style pipe but did not like it at all so I bought this one because it was cheap. It works quite well for the money I am very happy.
http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXBMH0
I never understood why HPI runs composite tuned pipes; as for the best performance you need something that will hold heat. Matter of fact steel would be best as it holds heat better then aluminum but I guess then the weight factor comes in to play. The only steel pipes I know of are for big blocks.
Keep us posted and good luck. Looking forward to seeing pictures. I need to post some of my beat up MT 1 ¾.