I would agree w/ joneser4u, unless you are racing in sanctioned races & have requirements, anything that is compatible w/ the T-Maxx would also be compatible w/ the 4-Tec. They have the exact same engine, the TRX 2.5.
You just need to make sure that if you get one that fits on the Maxx, triple check to make sure it will fit on the 4-Tec. All you need to look at is the length, it should be no bigger than 5 inches, b/c if it is, it might rub on the front tire. Also check to make sure that you can flip the pipe upside down b/c on the maxx the stinger points out to the right. But on the 4-Tec the stinger would be pointing out to the left.
I had the same question. I'm going to try to fit a CVEC TMAXX Dual Exhaust Kit to come out the rear of my 4 tec. I don't like doing a nice job painting a body then have to cut a hole in the side of it. Haven't even run my 4 tec by the way. Just waiting for the snow to leave. I'll post pics when I get it done. Should be by Monday afternoon. Got some cutting to do at work.