If you don't need a EFRA legal pipe then the Dynamite 086 is the pipe to get for the 5 Port. They are affordable and the 5 Port really likes this pipe. Great economy too. I am running one on the 5 Port Turbo in my truggy and it rocks !!!
If you need a legal pipe then the either the 2047 or the LRP 2063 are great.
Massive Mods suggests the LRP pipe for truggy, as it has a little more torque, and the 2047 for buggy.